diff --git a/Cargo.lock b/Cargo.lock
index ff72f1418..a9e7c8b15 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5538,6 +5538,7 @@ dependencies = [
  "tracing-test",
  "unicode-width 0.2.1",
  "url",
+ "uv-cache-key",
  "uv-fs",
  "uv-normalize",
  "uv-pep440",
diff --git a/crates/uv-bench/benches/uv.rs b/crates/uv-bench/benches/uv.rs
index 2ba7a550c..f9599ea12 100644
--- a/crates/uv-bench/benches/uv.rs
+++ b/crates/uv-bench/benches/uv.rs
@@ -141,6 +141,9 @@ mod resolver {
         universal: bool,
     ) -> Result<ResolverOutput> {
         let build_isolation = BuildIsolation::default();
+        let extra_build_requires = uv_distribution::ExtraBuildRequires {
+            extra_build_dependencies: uv_workspace::pyproject::ExtraBuildDependencies::default(),
+        };
         let build_options = BuildOptions::default();
         let concurrency = Concurrency::default();
         let config_settings = ConfigSettings::default();
@@ -187,6 +190,7 @@ mod resolver {
             &config_settings,
             &config_settings_package,
             build_isolation,
+            &extra_build_requires,
             LinkMode::default(),
             &build_options,
             &hashes,
diff --git a/crates/uv-build-frontend/src/lib.rs b/crates/uv-build-frontend/src/lib.rs
index b815719ba..092fcec5c 100644
--- a/crates/uv-build-frontend/src/lib.rs
+++ b/crates/uv-build-frontend/src/lib.rs
@@ -4,6 +4,7 @@
 
 mod error;
 
+use std::borrow::Cow;
 use std::ffi::OsString;
 use std::fmt::Formatter;
 use std::fmt::Write;
@@ -42,6 +43,7 @@ use uv_static::EnvVars;
 use uv_types::{AnyErrorBuild, BuildContext, BuildIsolation, BuildStack, SourceBuildTrait};
 use uv_warnings::warn_user_once;
 use uv_workspace::WorkspaceCache;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 
 pub use crate::error::{Error, MissingHeaderCause};
 
@@ -281,6 +283,7 @@ impl SourceBuild {
         workspace_cache: &WorkspaceCache,
         config_settings: ConfigSettings,
         build_isolation: BuildIsolation<'_>,
+        extra_build_dependencies: &ExtraBuildDependencies,
         build_stack: &BuildStack,
         build_kind: BuildKind,
         mut environment_variables: FxHashMap<OsString, OsString>,
@@ -297,7 +300,6 @@ impl SourceBuild {
         };
 
         let default_backend: Pep517Backend = DEFAULT_BACKEND.clone();
-
         // Check if we have a PEP 517 build backend.
         let (pep517_backend, project) = Self::extract_pep517_backend(
             &source_tree,
@@ -322,6 +324,14 @@ impl SourceBuild {
             .or(fallback_package_version)
             .cloned();
 
+        let extra_build_dependencies = package_name
+            .as_ref()
+            .and_then(|name| extra_build_dependencies.get(name).cloned())
+            .unwrap_or_default()
+            .into_iter()
+            .map(Requirement::from)
+            .collect();
+
         // Create a virtual environment, or install into the shared environment if requested.
         let venv = if let Some(venv) = build_isolation.shared_environment(package_name.as_ref()) {
             venv.clone()
@@ -349,10 +359,13 @@ impl SourceBuild {
                 source_build_context,
                 &default_backend,
                 &pep517_backend,
+                extra_build_dependencies,
                 build_stack,
             )
             .await?;
 
+            // TODO(zanieb): We'll report `build-system.requires` here but it may include
+            // `extra-build-dependencies`
             build_context
                 .install(&resolved_requirements, &venv, build_stack)
                 .await
@@ -471,10 +484,13 @@ impl SourceBuild {
         source_build_context: SourceBuildContext,
         default_backend: &Pep517Backend,
         pep517_backend: &Pep517Backend,
+        extra_build_dependencies: Vec<Requirement>,
         build_stack: &BuildStack,
     ) -> Result<Resolution, Error> {
         Ok(
-            if pep517_backend.requirements == default_backend.requirements {
+            if pep517_backend.requirements == default_backend.requirements
+                && extra_build_dependencies.is_empty()
+            {
                 let mut resolution = source_build_context.default_resolution.lock().await;
                 if let Some(resolved_requirements) = &*resolution {
                     resolved_requirements.clone()
@@ -489,8 +505,21 @@ impl SourceBuild {
                     resolved_requirements
                 }
             } else {
+                // TODO(zanieb): It's unclear if we actually want to solve these together. We might
+                // want to perform a separate solve to allow conflicts?
+                let requirements = if extra_build_dependencies.is_empty() {
+                    Cow::Borrowed(&pep517_backend.requirements)
+                } else {
+                    // If there are extra build dependencies, we need to resolve them together with
+                    // the backend requirements.
+                    let mut requirements = pep517_backend.requirements.clone();
+                    requirements.extend(extra_build_dependencies);
+                    Cow::Owned(requirements)
+                };
+                // TODO(zanieb): We'll report `build-system.requires` here but it may include
+                // `extra-build-dependencies`
                 build_context
-                    .resolve(&pep517_backend.requirements, build_stack)
+                    .resolve(&requirements, build_stack)
                     .await
                     .map_err(|err| {
                         Error::RequirementsResolve("`build-system.requires`", err.into())
@@ -604,6 +633,7 @@ impl SourceBuild {
                             );
                         }
                     }
+
                     default_backend.clone()
                 };
                 Ok((backend, pyproject_toml.project))
diff --git a/crates/uv-cli/src/options.rs b/crates/uv-cli/src/options.rs
index ce3d8621a..290d9efe5 100644
--- a/crates/uv-cli/src/options.rs
+++ b/crates/uv-cli/src/options.rs
@@ -347,6 +347,7 @@ pub fn resolver_options(
         }),
         no_build_isolation: flag(no_build_isolation, build_isolation, "build-isolation"),
         no_build_isolation_package: Some(no_build_isolation_package),
+        extra_build_dependencies: None,
         exclude_newer,
         link_mode,
         no_build: flag(no_build, build, "build"),
@@ -465,6 +466,7 @@ pub fn resolver_installer_options(
         } else {
             Some(no_build_isolation_package)
         },
+        extra_build_dependencies: None,
         exclude_newer,
         link_mode,
         compile_bytecode: flag(compile_bytecode, no_compile_bytecode, "compile-bytecode"),
diff --git a/crates/uv-configuration/src/preview.rs b/crates/uv-configuration/src/preview.rs
index a3e2f4ee2..eaf49007a 100644
--- a/crates/uv-configuration/src/preview.rs
+++ b/crates/uv-configuration/src/preview.rs
@@ -15,6 +15,7 @@ bitflags::bitflags! {
         const PYLOCK = 1 << 3;
         const ADD_BOUNDS = 1 << 4;
         const PREFER_LOCKED_BUILDS = 1 << 5;
+        const EXTRA_BUILD_DEPENDENCIES = 1 << 6;
     }
 }
 
@@ -30,6 +31,7 @@ impl PreviewFeatures {
             Self::PYLOCK => "pylock",
             Self::ADD_BOUNDS => "add-bounds",
             Self::PREFER_LOCKED_BUILDS => "prefer-locked-builds",
+            Self::EXTRA_BUILD_DEPENDENCIES => "extra-build-dependencies",
             _ => panic!("`flag_as_str` can only be used for exactly one feature flag"),
         }
     }
@@ -73,6 +75,7 @@ impl FromStr for PreviewFeatures {
                 "pylock" => Self::PYLOCK,
                 "add-bounds" => Self::ADD_BOUNDS,
                 "prefer-locked-builds" => Self::PREFER_LOCKED_BUILDS,
+                "extra-build-dependencies" => Self::EXTRA_BUILD_DEPENDENCIES,
                 _ => {
                     warn_user_once!("Unknown preview feature: `{part}`");
                     continue;
@@ -239,6 +242,10 @@ mod tests {
             PreviewFeatures::PREFER_LOCKED_BUILDS.flag_as_str(),
             "prefer-locked-builds"
         );
+        assert_eq!(
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES.flag_as_str(),
+            "extra-build-dependencies"
+        );
     }
 
     #[test]
diff --git a/crates/uv-dispatch/src/lib.rs b/crates/uv-dispatch/src/lib.rs
index 5474e8af8..76a84c535 100644
--- a/crates/uv-dispatch/src/lib.rs
+++ b/crates/uv-dispatch/src/lib.rs
@@ -22,6 +22,7 @@ use uv_configuration::{
 };
 use uv_configuration::{BuildOutput, Concurrency};
 use uv_distribution::DistributionDatabase;
+use uv_distribution::ExtraBuildRequires;
 use uv_distribution_filename::DistFilename;
 use uv_distribution_types::{
     CachedDist, DependencyMetadata, Identifier, IndexCapabilities, IndexLocations,
@@ -88,6 +89,7 @@ pub struct BuildDispatch<'a> {
     shared_state: SharedState,
     dependency_metadata: &'a DependencyMetadata,
     build_isolation: BuildIsolation<'a>,
+    extra_build_requires: &'a ExtraBuildRequires,
     link_mode: uv_install_wheel::LinkMode,
     build_options: &'a BuildOptions,
     config_settings: &'a ConfigSettings,
@@ -117,6 +119,7 @@ impl<'a> BuildDispatch<'a> {
         config_settings: &'a ConfigSettings,
         config_settings_package: &'a PackageConfigSettings,
         build_isolation: BuildIsolation<'a>,
+        extra_build_requires: &'a ExtraBuildRequires,
         link_mode: uv_install_wheel::LinkMode,
         build_options: &'a BuildOptions,
         hasher: &'a HashStrategy,
@@ -140,6 +143,7 @@ impl<'a> BuildDispatch<'a> {
             config_settings,
             config_settings_package,
             build_isolation,
+            extra_build_requires,
             link_mode,
             build_options,
             hasher,
@@ -222,6 +226,10 @@ impl BuildContext for BuildDispatch<'_> {
         &self.workspace_cache
     }
 
+    fn extra_build_dependencies(&self) -> &uv_workspace::pyproject::ExtraBuildDependencies {
+        &self.extra_build_requires.extra_build_dependencies
+    }
+
     async fn resolve<'data>(
         &'data self,
         requirements: &'data [Requirement],
@@ -457,6 +465,7 @@ impl BuildContext for BuildDispatch<'_> {
             self.workspace_cache(),
             config_settings,
             self.build_isolation,
+            &self.extra_build_requires.extra_build_dependencies,
             &build_stack,
             build_kind,
             self.build_extra_env_vars.clone(),
diff --git a/crates/uv-distribution/src/lib.rs b/crates/uv-distribution/src/lib.rs
index 07958f715..6371d58af 100644
--- a/crates/uv-distribution/src/lib.rs
+++ b/crates/uv-distribution/src/lib.rs
@@ -3,8 +3,8 @@ pub use download::LocalWheel;
 pub use error::Error;
 pub use index::{BuiltWheelIndex, RegistryWheelIndex};
 pub use metadata::{
-    ArchiveMetadata, BuildRequires, FlatRequiresDist, LoweredRequirement, LoweringError, Metadata,
-    MetadataError, RequiresDist, SourcedDependencyGroups,
+    ArchiveMetadata, BuildRequires, ExtraBuildRequires, FlatRequiresDist, LoweredRequirement,
+    LoweringError, Metadata, MetadataError, RequiresDist, SourcedDependencyGroups,
 };
 pub use reporter::Reporter;
 pub use source::prune;
diff --git a/crates/uv-distribution/src/metadata/build_requires.rs b/crates/uv-distribution/src/metadata/build_requires.rs
index 99b528017..af218b470 100644
--- a/crates/uv-distribution/src/metadata/build_requires.rs
+++ b/crates/uv-distribution/src/metadata/build_requires.rs
@@ -4,7 +4,8 @@ use std::path::Path;
 use uv_configuration::SourceStrategy;
 use uv_distribution_types::{IndexLocations, Requirement};
 use uv_normalize::PackageName;
-use uv_workspace::pyproject::ToolUvSources;
+use uv_pypi_types::VerbatimParsedUrl;
+use uv_workspace::pyproject::{ExtraBuildDependencies, ToolUvSources};
 use uv_workspace::{
     DiscoveryOptions, MemberDiscovery, ProjectWorkspace, Workspace, WorkspaceCache,
 };
@@ -203,3 +204,93 @@ impl BuildRequires {
         })
     }
 }
+
+/// Lowered extra build dependencies with source resolution applied.
+#[derive(Debug, Clone)]
+pub struct ExtraBuildRequires {
+    pub extra_build_dependencies: ExtraBuildDependencies,
+}
+
+impl ExtraBuildRequires {
+    /// Lower extra build dependencies from a workspace, applying source resolution.
+    pub fn from_workspace(
+        extra_build_dependencies: ExtraBuildDependencies,
+        workspace: &Workspace,
+        index_locations: &IndexLocations,
+        source_strategy: SourceStrategy,
+    ) -> Result<Self, MetadataError> {
+        match source_strategy {
+            SourceStrategy::Enabled => {
+                // Collect project sources and indexes
+                let project_indexes = workspace
+                    .pyproject_toml()
+                    .tool
+                    .as_ref()
+                    .and_then(|tool| tool.uv.as_ref())
+                    .and_then(|uv| uv.index.as_deref())
+                    .unwrap_or(&[]);
+
+                let empty_sources = BTreeMap::default();
+                let project_sources = workspace
+                    .pyproject_toml()
+                    .tool
+                    .as_ref()
+                    .and_then(|tool| tool.uv.as_ref())
+                    .and_then(|uv| uv.sources.as_ref())
+                    .map(ToolUvSources::inner)
+                    .unwrap_or(&empty_sources);
+
+                // Lower each package's extra build dependencies
+                let mut result = ExtraBuildDependencies::default();
+                for (package_name, requirements) in extra_build_dependencies {
+                    let lowered: Vec<uv_pep508::Requirement<VerbatimParsedUrl>> = requirements
+                        .into_iter()
+                        .flat_map(|requirement| {
+                            let requirement_name = requirement.name.clone();
+                            let extra = requirement.marker.top_level_extra_name();
+                            let group = None;
+                            LoweredRequirement::from_requirement(
+                                requirement,
+                                None,
+                                workspace.install_path(),
+                                project_sources,
+                                project_indexes,
+                                extra.as_deref(),
+                                group,
+                                index_locations,
+                                workspace,
+                                None,
+                            )
+                            .map(
+                                move |requirement| match requirement {
+                                    Ok(requirement) => Ok(requirement.into_inner().into()),
+                                    Err(err) => Err(MetadataError::LoweringError(
+                                        requirement_name.clone(),
+                                        Box::new(err),
+                                    )),
+                                },
+                            )
+                        })
+                        .collect::<Result<Vec<_>, _>>()?;
+                    result.insert(package_name, lowered);
+                }
+                Ok(Self {
+                    extra_build_dependencies: result,
+                })
+            }
+            SourceStrategy::Disabled => {
+                // Without source resolution, just return the dependencies as-is
+                Ok(Self {
+                    extra_build_dependencies,
+                })
+            }
+        }
+    }
+
+    /// Create from pre-lowered dependencies (for non-workspace contexts).
+    pub fn from_lowered(extra_build_dependencies: ExtraBuildDependencies) -> Self {
+        Self {
+            extra_build_dependencies,
+        }
+    }
+}
diff --git a/crates/uv-distribution/src/metadata/mod.rs b/crates/uv-distribution/src/metadata/mod.rs
index a56a1c354..3375f9fe2 100644
--- a/crates/uv-distribution/src/metadata/mod.rs
+++ b/crates/uv-distribution/src/metadata/mod.rs
@@ -11,7 +11,7 @@ use uv_pypi_types::{HashDigests, ResolutionMetadata};
 use uv_workspace::dependency_groups::DependencyGroupError;
 use uv_workspace::{WorkspaceCache, WorkspaceError};
 
-pub use crate::metadata::build_requires::BuildRequires;
+pub use crate::metadata::build_requires::{BuildRequires, ExtraBuildRequires};
 pub use crate::metadata::dependency_groups::SourcedDependencyGroups;
 pub use crate::metadata::lowering::LoweredRequirement;
 pub use crate::metadata::lowering::LoweringError;
diff --git a/crates/uv-distribution/src/source/mod.rs b/crates/uv-distribution/src/source/mod.rs
index 66b6122e0..f269c1b87 100644
--- a/crates/uv-distribution/src/source/mod.rs
+++ b/crates/uv-distribution/src/source/mod.rs
@@ -404,6 +404,20 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         }
     }
 
+    /// Determine the extra build dependencies for the given package name.
+    fn extra_build_dependencies_for(
+        &self,
+        name: Option<&PackageName>,
+    ) -> &[uv_pep508::Requirement<uv_pypi_types::VerbatimParsedUrl>] {
+        name.and_then(|name| {
+            self.build_context
+                .extra_build_dependencies()
+                .get(name)
+                .map(|v| v.as_slice())
+        })
+        .unwrap_or(&[])
+    }
+
     /// Build a source distribution from a remote URL.
     async fn url<'data>(
         &self,
@@ -438,12 +452,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         let cache_shard = cache_shard.shard(revision.id());
         let source_dist_entry = cache_shard.entry(SOURCE);
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // If the cache contains a compatible wheel, return it.
@@ -614,12 +629,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             }
         }
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // Otherwise, we either need to build the metadata.
@@ -827,12 +843,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         let cache_shard = cache_shard.shard(revision.id());
         let source_entry = cache_shard.entry(SOURCE);
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // If the cache contains a compatible wheel, return it.
@@ -989,12 +1006,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             });
         }
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // Otherwise, we need to build a wheel.
@@ -1131,12 +1149,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         // freshness, since entries have to be fresher than the revision itself.
         let cache_shard = cache_shard.shard(revision.id());
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // If the cache contains a compatible wheel, return it.
@@ -1319,12 +1338,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             ));
         }
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // Otherwise, we need to build a wheel.
@@ -1524,12 +1544,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         // Acquire the advisory lock.
         let _lock = cache_shard.lock().await.map_err(Error::CacheWrite)?;
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // If the cache contains a compatible wheel, return it.
@@ -1827,12 +1848,13 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             ));
         }
 
-        // If there are build settings, we need to scope to a cache shard.
+        // If there are build settings or extra build dependencies, we need to scope to a cache shard.
         let config_settings = self.config_settings_for(source.name());
-        let cache_shard = if config_settings.is_empty() {
+        let extra_build_deps = self.extra_build_dependencies_for(source.name());
+        let cache_shard = if config_settings.is_empty() && extra_build_deps.is_empty() {
             cache_shard
         } else {
-            cache_shard.shard(cache_digest(&config_settings))
+            cache_shard.shard(cache_digest(&(&config_settings, extra_build_deps)))
         };
 
         // Otherwise, we need to build a wheel.
diff --git a/crates/uv-pep440/src/version.rs b/crates/uv-pep440/src/version.rs
index 223701692..bd1e0ffe2 100644
--- a/crates/uv-pep440/src/version.rs
+++ b/crates/uv-pep440/src/version.rs
@@ -114,6 +114,24 @@ impl Operator {
     pub fn is_star(self) -> bool {
         matches!(self, Self::EqualStar | Self::NotEqualStar)
     }
+
+    /// Returns the string representation of this operator.
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::Equal => "==",
+            // Beware, this doesn't print the star
+            Self::EqualStar => "==",
+            #[allow(deprecated)]
+            Self::ExactEqual => "===",
+            Self::NotEqual => "!=",
+            Self::NotEqualStar => "!=",
+            Self::TildeEqual => "~=",
+            Self::LessThan => "<",
+            Self::LessThanEqual => "<=",
+            Self::GreaterThan => ">",
+            Self::GreaterThanEqual => ">=",
+        }
+    }
 }
 
 impl FromStr for Operator {
@@ -150,21 +168,7 @@ impl FromStr for Operator {
 impl std::fmt::Display for Operator {
     /// Note the `EqualStar` is also `==`.
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let operator = match self {
-            Self::Equal => "==",
-            // Beware, this doesn't print the star
-            Self::EqualStar => "==",
-            #[allow(deprecated)]
-            Self::ExactEqual => "===",
-            Self::NotEqual => "!=",
-            Self::NotEqualStar => "!=",
-            Self::TildeEqual => "~=",
-            Self::LessThan => "<",
-            Self::LessThanEqual => "<=",
-            Self::GreaterThan => ">",
-            Self::GreaterThanEqual => ">=",
-        };
-
+        let operator = self.as_str();
         write!(f, "{operator}")
     }
 }
diff --git a/crates/uv-pep440/src/version_specifier.rs b/crates/uv-pep440/src/version_specifier.rs
index e111c5118..13e2687cf 100644
--- a/crates/uv-pep440/src/version_specifier.rs
+++ b/crates/uv-pep440/src/version_specifier.rs
@@ -48,6 +48,11 @@ impl VersionSpecifiers {
         Self(Box::new([]))
     }
 
+    /// The number of specifiers.
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
     /// Whether all specifiers match the given version.
     pub fn contains(&self, version: &Version) -> bool {
         self.iter().all(|specifier| specifier.contains(version))
diff --git a/crates/uv-pep508/Cargo.toml b/crates/uv-pep508/Cargo.toml
index cb23cfc04..c4830043b 100644
--- a/crates/uv-pep508/Cargo.toml
+++ b/crates/uv-pep508/Cargo.toml
@@ -19,6 +19,7 @@ doctest = false
 workspace = true
 
 [dependencies]
+uv-cache-key = { workspace = true }
 uv-fs = { workspace = true }
 uv-normalize = { workspace = true }
 uv-pep440 = { workspace = true }
diff --git a/crates/uv-pep508/src/lib.rs b/crates/uv-pep508/src/lib.rs
index 10e4142e7..b26742975 100644
--- a/crates/uv-pep508/src/lib.rs
+++ b/crates/uv-pep508/src/lib.rs
@@ -26,6 +26,7 @@ use std::str::FromStr;
 use serde::{Deserialize, Deserializer, Serialize, Serializer, de};
 use thiserror::Error;
 use url::Url;
+use uv_cache_key::{CacheKey, CacheKeyHasher};
 
 use cursor::Cursor;
 pub use marker::{
@@ -251,6 +252,52 @@ impl<T: Pep508Url> Serialize for Requirement<T> {
     }
 }
 
+impl<T: Pep508Url> CacheKey for Requirement<T>
+where
+    T: Display,
+{
+    fn cache_key(&self, state: &mut CacheKeyHasher) {
+        self.name.as_str().cache_key(state);
+
+        self.extras.len().cache_key(state);
+        for extra in &self.extras {
+            extra.as_str().cache_key(state);
+        }
+
+        // TODO(zanieb): We inline cache key handling for the child types here, but we could
+        // move the implementations to the children. The intent here was to limit the scope of
+        // types exposing the `CacheKey` trait for now.
+        if let Some(version_or_url) = &self.version_or_url {
+            1u8.cache_key(state);
+            match version_or_url {
+                VersionOrUrl::VersionSpecifier(spec) => {
+                    0u8.cache_key(state);
+                    spec.len().cache_key(state);
+                    for specifier in spec.iter() {
+                        specifier.operator().as_str().cache_key(state);
+                        specifier.version().to_string().cache_key(state);
+                    }
+                }
+                VersionOrUrl::Url(url) => {
+                    1u8.cache_key(state);
+                    url.to_string().cache_key(state);
+                }
+            }
+        } else {
+            0u8.cache_key(state);
+        }
+
+        if let Some(marker) = self.marker.contents() {
+            1u8.cache_key(state);
+            marker.to_string().cache_key(state);
+        } else {
+            0u8.cache_key(state);
+        }
+
+        // `origin` is intentionally omitted
+    }
+}
+
 impl<T: Pep508Url> Requirement<T> {
     /// Returns whether the markers apply for the given environment
     pub fn evaluate_markers(&self, env: &MarkerEnvironment, extras: &[ExtraName]) -> bool {
diff --git a/crates/uv-scripts/src/lib.rs b/crates/uv-scripts/src/lib.rs
index b80cdc219..b0b9fde2e 100644
--- a/crates/uv-scripts/src/lib.rs
+++ b/crates/uv-scripts/src/lib.rs
@@ -381,6 +381,8 @@ pub struct ToolUv {
     pub override_dependencies: Option<Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>,
     pub constraint_dependencies: Option<Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>,
     pub build_constraint_dependencies: Option<Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>,
+    pub extra_build_dependencies:
+        Option<BTreeMap<PackageName, Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>>,
     pub sources: Option<BTreeMap<PackageName, Sources>>,
 }
 
diff --git a/crates/uv-settings/src/combine.rs b/crates/uv-settings/src/combine.rs
index b8d2e3c28..8af9db328 100644
--- a/crates/uv-settings/src/combine.rs
+++ b/crates/uv-settings/src/combine.rs
@@ -1,5 +1,5 @@
-use std::num::NonZeroUsize;
 use std::path::PathBuf;
+use std::{collections::BTreeMap, num::NonZeroUsize};
 
 use url::Url;
 
@@ -121,6 +121,21 @@ impl<T> Combine for Option<Vec<T>> {
     }
 }
 
+impl<K: Ord, T> Combine for Option<BTreeMap<K, Vec<T>>> {
+    /// Combine two maps of vecs by combining their vecs
+    fn combine(self, other: Option<BTreeMap<K, Vec<T>>>) -> Option<BTreeMap<K, Vec<T>>> {
+        match (self, other) {
+            (Some(mut a), Some(b)) => {
+                for (key, value) in b {
+                    a.entry(key).or_default().extend(value);
+                }
+                Some(a)
+            }
+            (a, b) => a.or(b),
+        }
+    }
+}
+
 impl Combine for Option<ConfigSettings> {
     /// Combine two maps by merging the map in `self` with the map in `other`, if they're both
     /// `Some`.
diff --git a/crates/uv-settings/src/lib.rs b/crates/uv-settings/src/lib.rs
index d56d512e0..c614880cb 100644
--- a/crates/uv-settings/src/lib.rs
+++ b/crates/uv-settings/src/lib.rs
@@ -317,6 +317,7 @@ fn warn_uv_toml_masked_fields(options: &Options) {
                 config_settings_package,
                 no_build_isolation,
                 no_build_isolation_package,
+                extra_build_dependencies,
                 exclude_newer,
                 link_mode,
                 compile_bytecode,
@@ -445,6 +446,9 @@ fn warn_uv_toml_masked_fields(options: &Options) {
     if no_build_isolation_package.is_some() {
         masked_fields.push("no-build-isolation-package");
     }
+    if extra_build_dependencies.is_some() {
+        masked_fields.push("extra-build-dependencies");
+    }
     if exclude_newer.is_some() {
         masked_fields.push("exclude-newer");
     }
diff --git a/crates/uv-settings/src/settings.rs b/crates/uv-settings/src/settings.rs
index 254cb204b..6515f5835 100644
--- a/crates/uv-settings/src/settings.rs
+++ b/crates/uv-settings/src/settings.rs
@@ -21,7 +21,7 @@ use uv_redacted::DisplaySafeUrl;
 use uv_resolver::{AnnotationStyle, ExcludeNewer, ForkStrategy, PrereleaseMode, ResolutionMode};
 use uv_static::EnvVars;
 use uv_torch::TorchMode;
-use uv_workspace::pyproject_mut::AddBoundsKind;
+use uv_workspace::{pyproject::ExtraBuildDependencies, pyproject_mut::AddBoundsKind};
 
 /// A `pyproject.toml` with an (optional) `[tool.uv]` section.
 #[allow(dead_code)]
@@ -373,6 +373,7 @@ pub struct ResolverOptions {
     pub no_binary_package: Option<Vec<PackageName>>,
     pub no_build_isolation: Option<bool>,
     pub no_build_isolation_package: Option<Vec<PackageName>>,
+    pub extra_build_dependencies: Option<ExtraBuildDependencies>,
     pub no_sources: Option<bool>,
     pub build_dependency_strategy: Option<BuildDependencyStrategy>,
 }
@@ -643,6 +644,20 @@ pub struct ResolverInstallerOptions {
     "#
     )]
     pub no_build_isolation_package: Option<Vec<PackageName>>,
+    /// Additional build dependencies for packages.
+    ///
+    /// This allows extending the PEP 517 build environment for the project's dependencies with
+    /// additional packages. This is useful for packages that assume the presence of packages, like,
+    /// `pip`, and do not declare them as build dependencies.
+    #[option(
+        default = "[]",
+        value_type = "dict",
+        example = r#"
+        [extra-build-dependencies] 
+        pytest = ["setuptools"]
+    "#
+    )]
+    pub extra_build_dependencies: Option<ExtraBuildDependencies>,
     /// Limit candidate packages to those that were uploaded prior to a given point in time.
     ///
     /// Accepts a superset of [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) (e.g.,
@@ -1139,6 +1154,20 @@ pub struct PipOptions {
         "#
     )]
     pub no_build_isolation_package: Option<Vec<PackageName>>,
+    /// Additional build dependencies for packages.
+    ///
+    /// This allows extending the PEP 517 build environment for the project's dependencies with
+    /// additional packages. This is useful for packages that assume the presence of packages, like,
+    /// `pip`, and do not declare them as build dependencies.
+    #[option(
+        default = "[]",
+        value_type = "dict",
+        example = r#"
+            [extra-build-dependencies]
+            pytest = ["setuptools"]
+        "#
+    )]
+    pub extra_build_dependencies: Option<ExtraBuildDependencies>,
     /// Validate the Python environment, to detect packages with missing dependencies and other
     /// issues.
     #[option(
@@ -1704,6 +1733,7 @@ impl From<ResolverInstallerOptions> for ResolverOptions {
             no_binary_package: value.no_binary_package,
             no_build_isolation: value.no_build_isolation,
             no_build_isolation_package: value.no_build_isolation_package,
+            extra_build_dependencies: value.extra_build_dependencies,
             no_sources: value.no_sources,
             build_dependency_strategy: value.build_dependency_strategy,
         }
@@ -1761,6 +1791,7 @@ pub struct ToolOptions {
     pub config_settings_package: Option<PackageConfigSettings>,
     pub no_build_isolation: Option<bool>,
     pub no_build_isolation_package: Option<Vec<PackageName>>,
+    pub extra_build_dependencies: Option<ExtraBuildDependencies>,
     pub exclude_newer: Option<ExcludeNewer>,
     pub link_mode: Option<LinkMode>,
     pub compile_bytecode: Option<bool>,
@@ -1789,6 +1820,7 @@ impl From<ResolverInstallerOptions> for ToolOptions {
             config_settings_package: value.config_settings_package,
             no_build_isolation: value.no_build_isolation,
             no_build_isolation_package: value.no_build_isolation_package,
+            extra_build_dependencies: value.extra_build_dependencies,
             exclude_newer: value.exclude_newer,
             link_mode: value.link_mode,
             compile_bytecode: value.compile_bytecode,
@@ -1819,6 +1851,7 @@ impl From<ToolOptions> for ResolverInstallerOptions {
             config_settings_package: value.config_settings_package,
             no_build_isolation: value.no_build_isolation,
             no_build_isolation_package: value.no_build_isolation_package,
+            extra_build_dependencies: value.extra_build_dependencies,
             exclude_newer: value.exclude_newer,
             link_mode: value.link_mode,
             compile_bytecode: value.compile_bytecode,
@@ -1873,6 +1906,7 @@ pub struct OptionsWire {
     config_settings_package: Option<PackageConfigSettings>,
     no_build_isolation: Option<bool>,
     no_build_isolation_package: Option<Vec<PackageName>>,
+    extra_build_dependencies: Option<ExtraBuildDependencies>,
     exclude_newer: Option<ExcludeNewer>,
     link_mode: Option<LinkMode>,
     compile_bytecode: Option<bool>,
@@ -1992,6 +2026,7 @@ impl From<OptionsWire> for Options {
             sources,
             default_groups,
             dependency_groups,
+            extra_build_dependencies,
             dev_dependencies,
             managed,
             package,
@@ -2033,6 +2068,7 @@ impl From<OptionsWire> for Options {
                 config_settings_package,
                 no_build_isolation,
                 no_build_isolation_package,
+                extra_build_dependencies,
                 exclude_newer,
                 link_mode,
                 compile_bytecode,
diff --git a/crates/uv-types/src/traits.rs b/crates/uv-types/src/traits.rs
index e3f4ee012..875742da9 100644
--- a/crates/uv-types/src/traits.rs
+++ b/crates/uv-types/src/traits.rs
@@ -101,6 +101,9 @@ pub trait BuildContext {
     /// Workspace discovery caching.
     fn workspace_cache(&self) -> &WorkspaceCache;
 
+    /// Get the extra build dependencies.
+    fn extra_build_dependencies(&self) -> &uv_workspace::pyproject::ExtraBuildDependencies;
+
     /// Resolve the given requirements into a ready-to-install set of package versions.
     fn resolve<'a>(
         &'a self,
diff --git a/crates/uv-workspace/src/pyproject.rs b/crates/uv-workspace/src/pyproject.rs
index b02dadc5d..4a1c9231c 100644
--- a/crates/uv-workspace/src/pyproject.rs
+++ b/crates/uv-workspace/src/pyproject.rs
@@ -378,6 +378,21 @@ pub struct ToolUv {
     )]
     pub dependency_groups: Option<ToolUvDependencyGroups>,
 
+    /// Additional build dependencies for packages.
+    ///
+    /// This allows extending the PEP 517 build environment for the project's dependencies with
+    /// additional packages. This is useful for packages that assume the presence of packages, like,
+    /// `pip`, and do not declare them as build dependencies.
+    #[option(
+        default = "[]",
+        value_type = "dict",
+        example = r#"
+            [tool.uv.extra-build-dependencies]
+            pytest = ["pip"]
+        "#
+    )]
+    pub extra_build_dependencies: Option<ToolUvExtraBuildDependencies>,
+
     /// The project's development dependencies.
     ///
     /// Development dependencies will be installed by default in `uv run` and `uv sync`, but will
@@ -749,6 +764,70 @@ pub struct DependencyGroupSettings {
     pub requires_python: Option<VersionSpecifiers>,
 }
 
+pub type ExtraBuildDependencies =
+    BTreeMap<PackageName, Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>;
+
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(test, derive(Serialize))]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolUvExtraBuildDependencies(ExtraBuildDependencies);
+
+impl ToolUvExtraBuildDependencies {
+    /// Returns the underlying `BTreeMap` of group names to settings.
+    pub fn inner(&self) -> &ExtraBuildDependencies {
+        &self.0
+    }
+
+    /// Convert the [`ToolUvExtraBuildDependencies`] into its inner `BTreeMap`.
+    #[must_use]
+    pub fn into_inner(self) -> ExtraBuildDependencies {
+        self.0
+    }
+}
+
+/// Ensure that all keys in the TOML table are unique.
+impl<'de> serde::de::Deserialize<'de> for ToolUvExtraBuildDependencies {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct DependenciesVisitor;
+
+        impl<'de> serde::de::Visitor<'de> for DependenciesVisitor {
+            type Value = ToolUvExtraBuildDependencies;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a map with unique keys")
+            }
+
+            fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+            where
+                M: serde::de::MapAccess<'de>,
+            {
+                let mut groups = BTreeMap::new();
+                while let Some((key, value)) = access
+                    .next_entry::<PackageName, Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>()?
+                {
+                    match groups.entry(key) {
+                        std::collections::btree_map::Entry::Occupied(entry) => {
+                            return Err(serde::de::Error::custom(format!(
+                                "duplicate extra-build-dependencies for `{}`",
+                                entry.key()
+                            )));
+                        }
+                        std::collections::btree_map::Entry::Vacant(entry) => {
+                            entry.insert(value);
+                        }
+                    }
+                }
+                Ok(ToolUvExtraBuildDependencies(groups))
+            }
+        }
+
+        deserializer.deserialize_map(DependenciesVisitor)
+    }
+}
+
 #[derive(Deserialize, OptionsMetadata, Default, Debug, Clone, PartialEq, Eq)]
 #[cfg_attr(test, derive(Serialize))]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
diff --git a/crates/uv-workspace/src/workspace.rs b/crates/uv-workspace/src/workspace.rs
index 09f2b692a..53342865e 100644
--- a/crates/uv-workspace/src/workspace.rs
+++ b/crates/uv-workspace/src/workspace.rs
@@ -1970,6 +1970,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
@@ -2070,6 +2071,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
@@ -2283,6 +2285,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
@@ -2392,6 +2395,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
@@ -2514,6 +2518,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
@@ -2610,6 +2615,7 @@ mod tests {
                       "package": null,
                       "default-groups": null,
                       "dependency-groups": null,
+                      "extra-build-dependencies": null,
                       "dev-dependencies": null,
                       "override-dependencies": null,
                       "constraint-dependencies": null,
diff --git a/crates/uv/src/commands/build_frontend.rs b/crates/uv/src/commands/build_frontend.rs
index c817bc3e5..420ad4253 100644
--- a/crates/uv/src/commands/build_frontend.rs
+++ b/crates/uv/src/commands/build_frontend.rs
@@ -38,6 +38,7 @@ use uv_requirements::RequirementsSource;
 use uv_resolver::{ExcludeNewer, FlatIndex, Preferences};
 use uv_settings::PythonInstallMirrors;
 use uv_types::{AnyErrorBuild, BuildContext, BuildIsolation, BuildStack, HashStrategy};
+use uv_workspace::pyproject::ExtraBuildDependencies;
 use uv_workspace::{DiscoveryOptions, Workspace, WorkspaceCache, WorkspaceError};
 
 use crate::commands::ExitStatus;
@@ -200,6 +201,7 @@ async fn build_impl(
         config_settings_package,
         no_build_isolation,
         no_build_isolation_package,
+        extra_build_dependencies,
         exclude_newer,
         link_mode,
         upgrade: _,
@@ -347,6 +349,7 @@ async fn build_impl(
             build_constraints,
             *no_build_isolation,
             no_build_isolation_package,
+            extra_build_dependencies,
             *index_strategy,
             *keyring_provider,
             *exclude_newer,
@@ -425,6 +428,7 @@ async fn build_package(
     build_constraints: &[RequirementsSource],
     no_build_isolation: bool,
     no_build_isolation_package: &[PackageName],
+    extra_build_dependencies: &ExtraBuildDependencies,
     index_strategy: IndexStrategy,
     keyring_provider: KeyringProviderType,
     exclude_newer: Option<ExcludeNewer>,
@@ -561,6 +565,8 @@ async fn build_package(
     let workspace_cache = WorkspaceCache::default();
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         cache,
@@ -574,6 +580,7 @@ async fn build_package(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         build_options,
         &hasher,
diff --git a/crates/uv/src/commands/pip/compile.rs b/crates/uv/src/commands/pip/compile.rs
index 156905ff1..49579b4da 100644
--- a/crates/uv/src/commands/pip/compile.rs
+++ b/crates/uv/src/commands/pip/compile.rs
@@ -14,8 +14,8 @@ use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
     BuildOptions, Concurrency, ConfigSettings, Constraints, ExportFormat, ExtrasSpecification,
-    IndexStrategy, NoBinary, NoBuild, PackageConfigSettings, Preview, Reinstall, SourceStrategy,
-    Upgrade,
+    IndexStrategy, NoBinary, NoBuild, PackageConfigSettings, Preview, PreviewFeatures, Reinstall,
+    SourceStrategy, Upgrade,
 };
 use uv_configuration::{KeyringProviderType, TargetTriple};
 use uv_dispatch::{BuildDispatch, SharedState};
@@ -44,8 +44,9 @@ use uv_resolver::{
 };
 use uv_torch::{TorchMode, TorchStrategy};
 use uv_types::{BuildIsolation, EmptyInstalledPackages, HashStrategy};
-use uv_warnings::warn_user;
+use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::WorkspaceCache;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 
 use crate::commands::pip::loggers::DefaultResolveLogger;
 use crate::commands::pip::{operations, resolution_environment};
@@ -95,6 +96,7 @@ pub(crate) async fn pip_compile(
     config_settings_package: PackageConfigSettings,
     no_build_isolation: bool,
     no_build_isolation_package: Vec<PackageName>,
+    extra_build_dependencies: &ExtraBuildDependencies,
     build_options: BuildOptions,
     mut python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
@@ -112,6 +114,15 @@ pub(crate) async fn pip_compile(
     printer: Printer,
     preview: Preview,
 ) -> Result<ExitStatus> {
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
     // If the user provides a `pyproject.toml` or other TOML file as the output file, raise an
     // error.
     if output_file
@@ -469,6 +480,8 @@ pub(crate) async fn pip_compile(
             .map(|constraint| constraint.requirement.clone()),
     );
 
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         &cache,
@@ -482,6 +495,7 @@ pub(crate) async fn pip_compile(
         &config_settings,
         &config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         &build_options,
         &build_hashes,
diff --git a/crates/uv/src/commands/pip/install.rs b/crates/uv/src/commands/pip/install.rs
index 9b7f85c9d..8e081819c 100644
--- a/crates/uv/src/commands/pip/install.rs
+++ b/crates/uv/src/commands/pip/install.rs
@@ -36,8 +36,9 @@ use uv_resolver::{
 };
 use uv_torch::{TorchMode, TorchStrategy};
 use uv_types::{BuildIsolation, HashStrategy};
-use uv_warnings::warn_user;
+use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::WorkspaceCache;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 
 use crate::commands::pip::loggers::{DefaultInstallLogger, DefaultResolveLogger, InstallLogger};
 use crate::commands::pip::operations::Modifications;
@@ -78,6 +79,7 @@ pub(crate) async fn pip_install(
     config_settings_package: &PackageConfigSettings,
     no_build_isolation: bool,
     no_build_isolation_package: Vec<PackageName>,
+    extra_build_dependencies: &ExtraBuildDependencies,
     build_options: BuildOptions,
     modifications: Modifications,
     python_version: Option<PythonVersion>,
@@ -99,6 +101,15 @@ pub(crate) async fn pip_install(
 ) -> anyhow::Result<ExitStatus> {
     let start = std::time::Instant::now();
 
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
     let client_builder = BaseClientBuilder::new()
         .retries_from_env()?
         .connectivity(network_settings.connectivity)
@@ -413,6 +424,8 @@ pub(crate) async fn pip_install(
     let state = SharedState::default();
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         &cache,
@@ -426,6 +439,7 @@ pub(crate) async fn pip_install(
         config_settings,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         &build_options,
         &build_hasher,
diff --git a/crates/uv/src/commands/pip/sync.rs b/crates/uv/src/commands/pip/sync.rs
index a7bd36652..562641ecf 100644
--- a/crates/uv/src/commands/pip/sync.rs
+++ b/crates/uv/src/commands/pip/sync.rs
@@ -32,8 +32,9 @@ use uv_resolver::{
 };
 use uv_torch::{TorchMode, TorchStrategy};
 use uv_types::{BuildIsolation, HashStrategy};
-use uv_warnings::warn_user;
+use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::WorkspaceCache;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 
 use crate::commands::pip::loggers::{DefaultInstallLogger, DefaultResolveLogger};
 use crate::commands::pip::operations::Modifications;
@@ -67,6 +68,7 @@ pub(crate) async fn pip_sync(
     config_settings_package: &PackageConfigSettings,
     no_build_isolation: bool,
     no_build_isolation_package: Vec<PackageName>,
+    extra_build_dependencies: &ExtraBuildDependencies,
     build_options: BuildOptions,
     python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
@@ -85,6 +87,15 @@ pub(crate) async fn pip_sync(
     printer: Printer,
     preview: Preview,
 ) -> Result<ExitStatus> {
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
     let client_builder = BaseClientBuilder::new()
         .retries_from_env()?
         .connectivity(network_settings.connectivity)
@@ -348,6 +359,8 @@ pub(crate) async fn pip_sync(
     let state = SharedState::default();
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         &cache,
@@ -361,6 +374,7 @@ pub(crate) async fn pip_sync(
         config_settings,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         &build_options,
         &build_hasher,
diff --git a/crates/uv/src/commands/project/add.rs b/crates/uv/src/commands/project/add.rs
index a66d2b517..cc8e71b3d 100644
--- a/crates/uv/src/commands/project/add.rs
+++ b/crates/uv/src/commands/project/add.rs
@@ -104,6 +104,15 @@ pub(crate) async fn add(
         );
     }
 
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !settings.resolver.extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
     for source in &requirements {
         match source {
             RequirementsSource::PyprojectToml(_) => {
@@ -457,6 +466,18 @@ pub(crate) async fn add(
             };
 
             // Create a build dispatch.
+            let extra_build_requires = if let AddTarget::Project(project, _) = &target {
+                uv_distribution::ExtraBuildRequires::from_workspace(
+                    settings.resolver.extra_build_dependencies.clone(),
+                    project.workspace(),
+                    &settings.resolver.index_locations,
+                    settings.resolver.sources,
+                )?
+            } else {
+                uv_distribution::ExtraBuildRequires::from_lowered(
+                    settings.resolver.extra_build_dependencies.clone(),
+                )
+            };
             let build_dispatch = BuildDispatch::new(
                 &client,
                 cache,
@@ -470,6 +491,7 @@ pub(crate) async fn add(
                 &settings.resolver.config_setting,
                 &settings.resolver.config_settings_package,
                 build_isolation,
+                &extra_build_requires,
                 settings.resolver.link_mode,
                 &settings.resolver.build_options,
                 &build_hasher,
@@ -1312,6 +1334,7 @@ impl PythonTarget {
 
 /// Represents the destination where dependencies are added, either to a project or a script.
 #[derive(Debug, Clone)]
+#[allow(clippy::large_enum_variant)]
 pub(super) enum AddTarget {
     /// A PEP 723 script, with inline metadata.
     Script(Pep723Script, Box<Interpreter>),
@@ -1420,6 +1443,7 @@ impl AddTarget {
 }
 
 #[derive(Debug, Clone)]
+#[allow(clippy::large_enum_variant)]
 enum AddTargetSnapshot {
     Script(Pep723Script, Option<Vec<u8>>),
     Project(VirtualProject, Option<Vec<u8>>),
diff --git a/crates/uv/src/commands/project/export.rs b/crates/uv/src/commands/project/export.rs
index 6b06e493a..df839be08 100644
--- a/crates/uv/src/commands/project/export.rs
+++ b/crates/uv/src/commands/project/export.rs
@@ -32,6 +32,7 @@ use crate::printer::Printer;
 use crate::settings::{NetworkSettings, ResolverSettings};
 
 #[derive(Debug, Clone)]
+#[allow(clippy::large_enum_variant)]
 enum ExportTarget {
     /// A PEP 723 script, with inline metadata.
     Script(Pep723Script),
diff --git a/crates/uv/src/commands/project/lock.rs b/crates/uv/src/commands/project/lock.rs
index e4848daba..b15b5721a 100644
--- a/crates/uv/src/commands/project/lock.rs
+++ b/crates/uv/src/commands/project/lock.rs
@@ -42,7 +42,7 @@ use crate::commands::pip::loggers::{DefaultResolveLogger, ResolveLogger, Summary
 use crate::commands::project::lock_target::LockTarget;
 use crate::commands::project::{
     ProjectError, ProjectInterpreter, ScriptInterpreter, UniversalState,
-    init_script_python_requirement,
+    init_script_python_requirement, script_specification,
 };
 use crate::commands::reporters::{PythonDownloadReporter, ResolverReporter};
 use crate::commands::{ExitStatus, ScriptPath, diagnostics, pip};
@@ -435,6 +435,7 @@ async fn do_lock(
         config_settings_package,
         no_build_isolation,
         no_build_isolation_package,
+        extra_build_dependencies,
         exclude_newer,
         link_mode,
         upgrade,
@@ -453,6 +454,15 @@ async fn do_lock(
         );
     }
 
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
     // Collect the requirements, etc.
     let members = target.members();
     let packages = target.packages();
@@ -695,6 +705,24 @@ async fn do_lock(
     };
 
     // Create a build dispatch.
+    let extra_build_requires = match &target {
+        LockTarget::Workspace(workspace) => uv_distribution::ExtraBuildRequires::from_workspace(
+            extra_build_dependencies.clone(),
+            workspace,
+            index_locations,
+            *sources,
+        )?,
+        LockTarget::Script(script) => {
+            // Try to get extra build dependencies from the script metadata
+            script_specification(Pep723ItemRef::Script(script), settings)?
+                .map(|spec| spec.extra_build_requires)
+                .unwrap_or_else(|| {
+                    uv_distribution::ExtraBuildRequires::from_lowered(
+                        extra_build_dependencies.clone(),
+                    )
+                })
+        }
+    };
     let build_dispatch = BuildDispatch::new(
         &client,
         cache,
@@ -708,6 +736,7 @@ async fn do_lock(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         *link_mode,
         build_options,
         &build_hasher,
diff --git a/crates/uv/src/commands/project/mod.rs b/crates/uv/src/commands/project/mod.rs
index 2579030ee..62cc66747 100644
--- a/crates/uv/src/commands/project/mod.rs
+++ b/crates/uv/src/commands/project/mod.rs
@@ -46,6 +46,7 @@ use uv_types::{BuildIsolation, EmptyInstalledPackages, HashStrategy};
 use uv_virtualenv::remove_virtualenv;
 use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::dependency_groups::DependencyGroupError;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 use uv_workspace::pyproject::PyProjectToml;
 use uv_workspace::{RequiresPythonSources, Workspace, WorkspaceCache};
 
@@ -1692,6 +1693,7 @@ pub(crate) async fn resolve_names(
                 link_mode,
                 no_build_isolation,
                 no_build_isolation_package,
+                extra_build_dependencies,
                 prerelease: _,
                 resolution: _,
                 sources,
@@ -1741,6 +1743,8 @@ pub(crate) async fn resolve_names(
     let build_hasher = HashStrategy::default();
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         cache,
@@ -1754,6 +1758,7 @@ pub(crate) async fn resolve_names(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         *link_mode,
         build_options,
         &build_hasher,
@@ -1847,6 +1852,7 @@ pub(crate) async fn resolve_environment(
         config_settings_package,
         no_build_isolation,
         no_build_isolation_package,
+        extra_build_dependencies,
         exclude_newer,
         link_mode,
         upgrade: _,
@@ -1951,6 +1957,8 @@ pub(crate) async fn resolve_environment(
     let workspace_cache = WorkspaceCache::default();
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let resolve_dispatch = BuildDispatch::new(
         &client,
         cache,
@@ -1964,6 +1972,7 @@ pub(crate) async fn resolve_environment(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         *link_mode,
         build_options,
         &build_hasher,
@@ -2032,6 +2041,7 @@ pub(crate) async fn sync_environment(
         config_settings_package,
         no_build_isolation,
         no_build_isolation_package,
+        extra_build_dependencies,
         exclude_newer,
         link_mode,
         compile_bytecode,
@@ -2091,6 +2101,8 @@ pub(crate) async fn sync_environment(
     };
 
     // Create a build dispatch.
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies.clone());
     let build_dispatch = BuildDispatch::new(
         &client,
         cache,
@@ -2104,6 +2116,7 @@ pub(crate) async fn sync_environment(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         build_options,
         &build_hasher,
@@ -2148,6 +2161,15 @@ pub(crate) async fn sync_environment(
     Ok(venv)
 }
 
+/// A script specification that includes both requirements and extra build dependencies.
+#[derive(Debug)]
+pub(crate) struct ScriptSpecification {
+    /// The requirements specification for the script.
+    pub(crate) requirements: RequirementsSpecification,
+    /// The extra build dependencies for the script.
+    pub(crate) extra_build_requires: uv_distribution::ExtraBuildRequires,
+}
+
 /// The result of updating a [`PythonEnvironment`] to satisfy a set of [`RequirementsSource`]s.
 #[derive(Debug)]
 pub(crate) struct EnvironmentUpdate {
@@ -2170,6 +2192,7 @@ pub(crate) async fn update_environment(
     spec: RequirementsSpecification,
     modifications: Modifications,
     build_constraints: Constraints,
+    extra_build_requires: uv_distribution::ExtraBuildRequires,
     settings: &ResolverInstallerSettings,
     network_settings: &NetworkSettings,
     state: &SharedState,
@@ -2200,6 +2223,7 @@ pub(crate) async fn update_environment(
                 link_mode,
                 no_build_isolation,
                 no_build_isolation_package,
+                extra_build_dependencies: _,
                 prerelease,
                 resolution,
                 sources,
@@ -2330,6 +2354,7 @@ pub(crate) async fn update_environment(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         *link_mode,
         build_options,
         &build_hasher,
@@ -2535,12 +2560,12 @@ pub(crate) fn detect_conflicts(
     Ok(())
 }
 
-/// Determine the [`RequirementsSpecification`] for a script.
+/// Determine the [`ScriptSpecification`] for a script.
 #[allow(clippy::result_large_err)]
 pub(crate) fn script_specification(
     script: Pep723ItemRef<'_>,
     settings: &ResolverSettings,
-) -> Result<Option<RequirementsSpecification>, ProjectError> {
+) -> Result<Option<ScriptSpecification>, ProjectError> {
     let Some(dependencies) = script.metadata().dependencies.as_ref() else {
         return Ok(None);
     };
@@ -2635,11 +2660,47 @@ pub(crate) fn script_specification(
         })
         .collect::<Result<Vec<_>, _>>()?;
 
-    Ok(Some(RequirementsSpecification::from_overrides(
-        requirements,
-        constraints,
-        overrides,
-    )))
+    // Collect any `tool.uv.extra-build-dependencies` from the script.
+    let empty = BTreeMap::default();
+    let script_extra_build_dependencies = script
+        .metadata()
+        .tool
+        .as_ref()
+        .and_then(|tool| tool.uv.as_ref())
+        .and_then(|uv| uv.extra_build_dependencies.as_ref())
+        .unwrap_or(&empty);
+
+    // Lower the extra build dependencies
+    let mut extra_build_dependencies = ExtraBuildDependencies::default();
+    for (name, requirements) in script_extra_build_dependencies {
+        let lowered_requirements: Vec<_> = requirements
+            .iter()
+            .cloned()
+            .flat_map(|requirement| {
+                LoweredRequirement::from_non_workspace_requirement(
+                    requirement,
+                    script_dir.as_ref(),
+                    script_sources,
+                    script_indexes,
+                    &settings.index_locations,
+                )
+                .map_ok(|req| req.into_inner().into())
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+        extra_build_dependencies.insert(name.clone(), lowered_requirements);
+    }
+
+    let extra_build_requires =
+        uv_distribution::ExtraBuildRequires::from_lowered(extra_build_dependencies);
+
+    Ok(Some(ScriptSpecification {
+        requirements: RequirementsSpecification::from_overrides(
+            requirements,
+            constraints,
+            overrides,
+        ),
+        extra_build_requires,
+    }))
 }
 
 /// Warn if the user provides (e.g.) an `--index-url` in a requirements file.
diff --git a/crates/uv/src/commands/project/remove.rs b/crates/uv/src/commands/project/remove.rs
index 1af4c818f..50c498833 100644
--- a/crates/uv/src/commands/project/remove.rs
+++ b/crates/uv/src/commands/project/remove.rs
@@ -386,6 +386,7 @@ pub(crate) async fn remove(
 
 /// Represents the destination where dependencies are added, either to a project or a script.
 #[derive(Debug)]
+#[allow(clippy::large_enum_variant)]
 enum RemoveTarget {
     /// A PEP 723 script, with inline metadata.
     Project(VirtualProject),
diff --git a/crates/uv/src/commands/project/run.rs b/crates/uv/src/commands/project/run.rs
index 20e11db18..c50788ad8 100644
--- a/crates/uv/src/commands/project/run.rs
+++ b/crates/uv/src/commands/project/run.rs
@@ -358,7 +358,9 @@ hint: If you are running a script with `{}` in the shebang, you may need to incl
             }
 
             // Install the script requirements, if necessary. Otherwise, use an isolated environment.
-            if let Some(spec) = script_specification((&script).into(), &settings.resolver)? {
+            if let Some(script_spec) = script_specification((&script).into(), &settings.resolver)? {
+                let spec = script_spec.requirements;
+                let script_extra_build_requires = script_spec.extra_build_requires;
                 let environment = ScriptEnvironment::get_or_init(
                     (&script).into(),
                     python.as_deref().map(PythonRequest::parse),
@@ -407,6 +409,7 @@ hint: If you are running a script with `{}` in the shebang, you may need to incl
                     spec,
                     modifications,
                     build_constraints.unwrap_or_default(),
+                    script_extra_build_requires,
                     &settings,
                     &network_settings,
                     &sync_state,
diff --git a/crates/uv/src/commands/project/sync.rs b/crates/uv/src/commands/project/sync.rs
index 9794c109e..2e80c3838 100644
--- a/crates/uv/src/commands/project/sync.rs
+++ b/crates/uv/src/commands/project/sync.rs
@@ -15,7 +15,7 @@ use uv_configuration::{
     BuildDependencyStrategy, Concurrency, Constraints, DependencyGroups,
     DependencyGroupsWithDefaults, DryRun, EditableMode, ExtrasSpecification,
     ExtrasSpecificationWithDefaults, HashCheckingMode, InstallOptions, Preview, PreviewFeatures,
-    TargetTriple,
+    TargetTriple, Upgrade,
 };
 use uv_dispatch::BuildDispatch;
 use uv_distribution_types::{
@@ -27,12 +27,13 @@ use uv_normalize::{DefaultExtras, DefaultGroups, PackageName};
 use uv_pep508::{MarkerTree, VersionOrUrl};
 use uv_pypi_types::{ParsedArchiveUrl, ParsedGitUrl, ParsedUrl};
 use uv_python::{PythonDownloads, PythonEnvironment, PythonPreference, PythonRequest};
-use uv_resolver::{FlatIndex, Installable, Lock, Preference, Preferences, ResolverEnvironment};
+use uv_requirements::RequirementsSpecification;
+use uv_resolver::{FlatIndex, ForkStrategy, Installable, Lock, Preference, Preferences, PrereleaseMode, ResolutionMode, ResolverEnvironment};
 use uv_scripts::{Pep723ItemRef, Pep723Script};
 use uv_settings::PythonInstallMirrors;
 use uv_types::{BuildIsolation, HashStrategy};
 use uv_warnings::{warn_user, warn_user_once};
-use uv_workspace::pyproject::Source;
+use uv_workspace::pyproject::{ExtraBuildDependencies, Source};
 use uv_workspace::{DiscoveryOptions, MemberDiscovery, VirtualProject, Workspace, WorkspaceCache};
 
 use crate::commands::pip::loggers::{DefaultInstallLogger, DefaultResolveLogger, InstallLogger};
@@ -48,7 +49,9 @@ use crate::commands::project::{
 };
 use crate::commands::{ExitStatus, diagnostics};
 use crate::printer::Printer;
-use crate::settings::{InstallerSettingsRef, NetworkSettings, ResolverInstallerSettings};
+use crate::settings::{
+    InstallerSettingsRef, NetworkSettings, ResolverInstallerSettings, ResolverSettings,
+};
 
 /// Sync the project environment.
 #[allow(clippy::fn_params_excessive_bools)]
@@ -223,8 +226,18 @@ pub(crate) async fn sync(
             }
 
             // Parse the requirements from the script.
-            let spec = script_specification(Pep723ItemRef::Script(script), &settings.resolver)?
-                .unwrap_or_default();
+            let script_spec =
+                script_specification(Pep723ItemRef::Script(script), &settings.resolver)?;
+            let (spec, script_extra_build_requires) = if let Some(script_spec) = script_spec {
+                (script_spec.requirements, script_spec.extra_build_requires)
+            } else {
+                (
+                    RequirementsSpecification::default(),
+                    uv_distribution::ExtraBuildRequires::from_lowered(
+                        ExtraBuildDependencies::default(),
+                    ),
+                )
+            };
 
             // Parse the build constraints from the script.
             let build_constraints = script
@@ -249,6 +262,7 @@ pub(crate) async fn sync(
                 spec,
                 modifications,
                 build_constraints.unwrap_or_default(),
+                script_extra_build_requires,
                 &settings,
                 &network_settings,
                 &PlatformState::default(),
@@ -495,6 +509,7 @@ fn identify_installation_target<'a>(
 }
 
 #[derive(Debug, Clone)]
+#[allow(clippy::large_enum_variant)]
 enum SyncTarget {
     /// Sync a project environment.
     Project(VirtualProject),
@@ -579,6 +594,7 @@ pub(super) async fn do_sync(
         config_settings_package,
         no_build_isolation,
         no_build_isolation_package,
+        extra_build_dependencies,
         exclude_newer,
         link_mode,
         compile_bytecode,
@@ -588,6 +604,57 @@ pub(super) async fn do_sync(
         build_dependency_strategy,
     } = settings;
 
+    if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+        && !extra_build_dependencies.is_empty()
+    {
+        warn_user_once!(
+            "The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+            PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+        );
+    }
+
+    // Lower the extra build dependencies with source resolution
+    let extra_build_requires = match &target {
+        InstallTarget::Workspace { workspace, .. }
+        | InstallTarget::Project { workspace, .. }
+        | InstallTarget::NonProjectWorkspace { workspace, .. } => {
+            uv_distribution::ExtraBuildRequires::from_workspace(
+                extra_build_dependencies.clone(),
+                workspace,
+                index_locations,
+                sources,
+            )?
+        }
+        InstallTarget::Script { script, .. } => {
+            // Try to get extra build dependencies from the script metadata
+            let resolver_settings = ResolverSettings {
+                build_options: build_options.clone(),
+                config_setting: config_setting.clone(),
+                config_settings_package: config_settings_package.clone(),
+                dependency_metadata: dependency_metadata.clone(),
+                exclude_newer,
+                fork_strategy: ForkStrategy::default(),
+                index_locations: index_locations.clone(),
+                index_strategy,
+                keyring_provider,
+                link_mode,
+                no_build_isolation,
+                no_build_isolation_package: no_build_isolation_package.to_vec(),
+                extra_build_dependencies: extra_build_dependencies.clone(),
+                prerelease: PrereleaseMode::default(),
+                resolution: ResolutionMode::default(),
+                sources,
+                upgrade: Upgrade::default(),
+                build_dependency_strategy: *build_dependency_strategy,
+            };
+            script_specification(Pep723ItemRef::Script(script), &resolver_settings)?
+                .map(|spec| spec.extra_build_requires)
+                .unwrap_or_else(|| uv_distribution::ExtraBuildRequires {
+                    extra_build_dependencies: ExtraBuildDependencies::default(),
+                })
+        }
+    };
+
     let client_builder = BaseClientBuilder::new()
         .retries_from_env()?
         .connectivity(network_settings.connectivity)
@@ -739,6 +806,7 @@ pub(super) async fn do_sync(
         config_setting,
         config_settings_package,
         build_isolation,
+        &extra_build_requires,
         link_mode,
         build_options,
         &build_hasher,
diff --git a/crates/uv/src/commands/project/tree.rs b/crates/uv/src/commands/project/tree.rs
index 521bf188e..01df3ac0c 100644
--- a/crates/uv/src/commands/project/tree.rs
+++ b/crates/uv/src/commands/project/tree.rs
@@ -203,6 +203,7 @@ pub(crate) async fn tree(
                 config_settings_package: _,
                 no_build_isolation: _,
                 no_build_isolation_package: _,
+                extra_build_dependencies: _,
                 exclude_newer: _,
                 link_mode: _,
                 upgrade: _,
diff --git a/crates/uv/src/commands/tool/install.rs b/crates/uv/src/commands/tool/install.rs
index 192597e93..6528f61d2 100644
--- a/crates/uv/src/commands/tool/install.rs
+++ b/crates/uv/src/commands/tool/install.rs
@@ -23,7 +23,7 @@ use uv_requirements::{RequirementsSource, RequirementsSpecification};
 use uv_settings::{PythonInstallMirrors, ResolverInstallerOptions, ToolOptions};
 use uv_tool::InstalledTools;
 use uv_warnings::warn_user;
-use uv_workspace::WorkspaceCache;
+use uv_workspace::{WorkspaceCache, pyproject::ExtraBuildDependencies};
 
 use crate::commands::ExitStatus;
 use crate::commands::pip::loggers::{DefaultInstallLogger, DefaultResolveLogger};
@@ -439,6 +439,7 @@ pub(crate) async fn install(
             spec,
             Modifications::Exact,
             Constraints::from_requirements(build_constraints.iter().cloned()),
+            uv_distribution::ExtraBuildRequires::from_lowered(ExtraBuildDependencies::default()),
             &settings,
             &network_settings,
             &state,
diff --git a/crates/uv/src/commands/tool/upgrade.rs b/crates/uv/src/commands/tool/upgrade.rs
index af42a9eef..f7bce3197 100644
--- a/crates/uv/src/commands/tool/upgrade.rs
+++ b/crates/uv/src/commands/tool/upgrade.rs
@@ -19,7 +19,7 @@ use uv_requirements::RequirementsSpecification;
 use uv_settings::{Combine, PythonInstallMirrors, ResolverInstallerOptions, ToolOptions};
 use uv_tool::InstalledTools;
 use uv_warnings::write_error_chain;
-use uv_workspace::WorkspaceCache;
+use uv_workspace::{WorkspaceCache, pyproject::ExtraBuildDependencies};
 
 use crate::commands::pip::loggers::{
     DefaultInstallLogger, SummaryResolveLogger, UpgradeInstallLogger,
@@ -337,6 +337,7 @@ async fn upgrade_tool(
             spec,
             Modifications::Exact,
             build_constraints,
+            uv_distribution::ExtraBuildRequires::from_lowered(ExtraBuildDependencies::default()),
             &settings,
             network_settings,
             &state,
diff --git a/crates/uv/src/commands/venv.rs b/crates/uv/src/commands/venv.rs
index 14225bd99..6d3b34a86 100644
--- a/crates/uv/src/commands/venv.rs
+++ b/crates/uv/src/commands/venv.rs
@@ -29,6 +29,7 @@ use uv_shell::{Shell, shlex_posix, shlex_windows};
 use uv_types::{AnyErrorBuild, BuildContext, BuildIsolation, BuildStack, HashStrategy};
 use uv_virtualenv::OnExisting;
 use uv_warnings::warn_user;
+use uv_workspace::pyproject::ExtraBuildDependencies;
 use uv_workspace::{DiscoveryOptions, VirtualProject, WorkspaceCache, WorkspaceError};
 
 use crate::commands::ExitStatus;
@@ -266,7 +267,8 @@ pub(crate) async fn venv(
 
         // Do not allow builds
         let build_options = BuildOptions::new(NoBinary::None, NoBuild::All);
-
+        let extra_build_requires =
+            uv_distribution::ExtraBuildRequires::from_lowered(ExtraBuildDependencies::default());
         // Prep the build context.
         let build_dispatch = BuildDispatch::new(
             &client,
@@ -281,6 +283,7 @@ pub(crate) async fn venv(
             &config_settings,
             &config_settings_package,
             BuildIsolation::Isolated,
+            &extra_build_requires,
             link_mode,
             &build_options,
             &build_hasher,
diff --git a/crates/uv/src/lib.rs b/crates/uv/src/lib.rs
index 4a937b0db..57a8a0320 100644
--- a/crates/uv/src/lib.rs
+++ b/crates/uv/src/lib.rs
@@ -28,7 +28,7 @@ use uv_cli::{
     ProjectCommand, PythonCommand, PythonNamespace, SelfCommand, SelfNamespace, ToolCommand,
     ToolNamespace, TopLevelArgs, compat::CompatArgs,
 };
-use uv_configuration::min_stack_size;
+use uv_configuration::{PreviewFeatures, min_stack_size};
 use uv_fs::{CWD, Simplified};
 #[cfg(feature = "self-update")]
 use uv_pep440::release_specifiers_to_ranges;
@@ -443,6 +443,16 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             // Resolve the settings from the command-line arguments and workspace configuration.
             let args = PipCompileSettings::resolve(args, filesystem);
             show_settings!(args);
+            if !args.settings.extra_build_dependencies.is_empty()
+                && !globals
+                    .preview
+                    .is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+            {
+                warn_user_once!(
+                    "The `extra-build-dependencies` setting is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+                    PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+                );
+            }
 
             // Initialize the cache.
             let cache = cache.init()?.with_refresh(
@@ -516,6 +526,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 args.settings.config_settings_package,
                 args.settings.no_build_isolation,
                 args.settings.no_build_isolation_package,
+                &args.settings.extra_build_dependencies,
                 args.settings.build_options,
                 args.settings.python_version,
                 args.settings.python_platform,
@@ -543,6 +554,16 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             // Resolve the settings from the command-line arguments and workspace configuration.
             let args = PipSyncSettings::resolve(args, filesystem);
             show_settings!(args);
+            if !args.settings.extra_build_dependencies.is_empty()
+                && !globals
+                    .preview
+                    .is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+            {
+                warn_user_once!(
+                    "The `extra-build-dependencies` setting is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+                    PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+                );
+            }
 
             // Initialize the cache.
             let cache = cache.init()?.with_refresh(
@@ -593,6 +614,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 &args.settings.config_settings_package,
                 args.settings.no_build_isolation,
                 args.settings.no_build_isolation_package,
+                &args.settings.extra_build_dependencies,
                 args.settings.build_options,
                 args.settings.python_version,
                 args.settings.python_platform,
@@ -621,6 +643,16 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             // Resolve the settings from the command-line arguments and workspace configuration.
             let mut args = PipInstallSettings::resolve(args, filesystem);
             show_settings!(args);
+            if !args.settings.extra_build_dependencies.is_empty()
+                && !globals
+                    .preview
+                    .is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)
+            {
+                warn_user_once!(
+                    "The `extra-build-dependencies` setting is experimental and may change without warning. Pass `--preview-features {}` to disable this warning.",
+                    PreviewFeatures::EXTRA_BUILD_DEPENDENCIES
+                );
+            }
 
             let mut requirements = Vec::with_capacity(
                 args.package.len() + args.editables.len() + args.requirements.len(),
@@ -735,6 +767,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 &args.settings.config_settings_package,
                 args.settings.no_build_isolation,
                 args.settings.no_build_isolation_package,
+                &args.settings.extra_build_dependencies,
                 args.settings.build_options,
                 args.modifications,
                 args.settings.python_version,
diff --git a/crates/uv/src/settings.rs b/crates/uv/src/settings.rs
index 8036f3c28..4d17e2982 100644
--- a/crates/uv/src/settings.rs
+++ b/crates/uv/src/settings.rs
@@ -44,7 +44,7 @@ use uv_settings::{
 use uv_static::EnvVars;
 use uv_torch::TorchMode;
 use uv_warnings::warn_user_once;
-use uv_workspace::pyproject::DependencyType;
+use uv_workspace::pyproject::{DependencyType, ExtraBuildDependencies};
 use uv_workspace::pyproject_mut::AddBoundsKind;
 
 use crate::commands::ToolRunCommand;
@@ -2708,6 +2708,7 @@ pub(crate) struct InstallerSettingsRef<'a> {
     pub(crate) config_settings_package: &'a PackageConfigSettings,
     pub(crate) no_build_isolation: bool,
     pub(crate) no_build_isolation_package: &'a [PackageName],
+    pub(crate) extra_build_dependencies: &'a ExtraBuildDependencies,
     pub(crate) exclude_newer: Option<ExcludeNewer>,
     pub(crate) link_mode: LinkMode,
     pub(crate) compile_bytecode: bool,
@@ -2735,6 +2736,7 @@ pub(crate) struct ResolverSettings {
     pub(crate) link_mode: LinkMode,
     pub(crate) no_build_isolation: bool,
     pub(crate) no_build_isolation_package: Vec<PackageName>,
+    pub(crate) extra_build_dependencies: ExtraBuildDependencies,
     pub(crate) prerelease: PrereleaseMode,
     pub(crate) resolution: ResolutionMode,
     pub(crate) sources: SourceStrategy,
@@ -2788,6 +2790,7 @@ impl From<ResolverOptions> for ResolverSettings {
             config_settings_package: value.config_settings_package.unwrap_or_default(),
             no_build_isolation: value.no_build_isolation.unwrap_or_default(),
             no_build_isolation_package: value.no_build_isolation_package.unwrap_or_default(),
+            extra_build_dependencies: value.extra_build_dependencies.unwrap_or_default(),
             exclude_newer: value.exclude_newer,
             link_mode: value.link_mode.unwrap_or_default(),
             sources: SourceStrategy::from_args(value.no_sources.unwrap_or_default()),
@@ -2878,6 +2881,7 @@ impl From<ResolverInstallerOptions> for ResolverInstallerSettings {
                 link_mode: value.link_mode.unwrap_or_default(),
                 no_build_isolation: value.no_build_isolation.unwrap_or_default(),
                 no_build_isolation_package: value.no_build_isolation_package.unwrap_or_default(),
+                extra_build_dependencies: value.extra_build_dependencies.unwrap_or_default(),
                 prerelease: value.prerelease.unwrap_or_default(),
                 resolution: value.resolution.unwrap_or_default(),
                 sources: SourceStrategy::from_args(value.no_sources.unwrap_or_default()),
@@ -2921,6 +2925,7 @@ pub(crate) struct PipSettings {
     pub(crate) torch_backend: Option<TorchMode>,
     pub(crate) no_build_isolation: bool,
     pub(crate) no_build_isolation_package: Vec<PackageName>,
+    pub(crate) extra_build_dependencies: ExtraBuildDependencies,
     pub(crate) build_options: BuildOptions,
     pub(crate) allow_empty_requirements: bool,
     pub(crate) strict: bool,
@@ -2988,6 +2993,7 @@ impl PipSettings {
             only_binary,
             no_build_isolation,
             no_build_isolation_package,
+            extra_build_dependencies,
             strict,
             extra,
             all_extras,
@@ -3046,6 +3052,7 @@ impl PipSettings {
             config_settings_package: top_level_config_settings_package,
             no_build_isolation: top_level_no_build_isolation,
             no_build_isolation_package: top_level_no_build_isolation_package,
+            extra_build_dependencies: top_level_extra_build_dependencies,
             exclude_newer: top_level_exclude_newer,
             link_mode: top_level_link_mode,
             compile_bytecode: top_level_compile_bytecode,
@@ -3082,6 +3089,8 @@ impl PipSettings {
         let no_build_isolation = no_build_isolation.combine(top_level_no_build_isolation);
         let no_build_isolation_package =
             no_build_isolation_package.combine(top_level_no_build_isolation_package);
+        let extra_build_dependencies =
+            extra_build_dependencies.combine(top_level_extra_build_dependencies);
         let exclude_newer = exclude_newer.combine(top_level_exclude_newer);
         let link_mode = link_mode.combine(top_level_link_mode);
         let compile_bytecode = compile_bytecode.combine(top_level_compile_bytecode);
@@ -3177,6 +3186,10 @@ impl PipSettings {
                 .no_build_isolation_package
                 .combine(no_build_isolation_package)
                 .unwrap_or_default(),
+            extra_build_dependencies: args
+                .extra_build_dependencies
+                .combine(extra_build_dependencies)
+                .unwrap_or_default(),
             config_setting: args
                 .config_settings
                 .combine(config_settings)
@@ -3281,6 +3294,7 @@ impl<'a> From<&'a ResolverInstallerSettings> for InstallerSettingsRef<'a> {
             config_settings_package: &settings.resolver.config_settings_package,
             no_build_isolation: settings.resolver.no_build_isolation,
             no_build_isolation_package: &settings.resolver.no_build_isolation_package,
+            extra_build_dependencies: &settings.resolver.extra_build_dependencies,
             exclude_newer: settings.resolver.exclude_newer,
             link_mode: settings.resolver.link_mode,
             compile_bytecode: settings.compile_bytecode,
diff --git a/crates/uv/tests/it/pip_install.rs b/crates/uv/tests/it/pip_install.rs
index 9ee284f3d..fc8dbf344 100644
--- a/crates/uv/tests/it/pip_install.rs
+++ b/crates/uv/tests/it/pip_install.rs
@@ -3920,16 +3920,17 @@ fn config_settings_registry() {
         .arg("iniconfig")
         .arg("--no-binary")
         .arg("iniconfig")
-        .arg("-C=global-option=build_ext"), @r###"
+        .arg("-C=global-option=build_ext"), @r"
     success: true
     exit_code: 0
     ----- stdout -----
 
     ----- stderr -----
     Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
     Installed 1 package in [TIME]
      + iniconfig==2.0.0
-    "###
+    "
     );
 
     // Uninstall the package.
diff --git a/crates/uv/tests/it/show_settings.rs b/crates/uv/tests/it/show_settings.rs
index 65555ba56..4c417e420 100644
--- a/crates/uv/tests/it/show_settings.rs
+++ b/crates/uv/tests/it/show_settings.rs
@@ -184,6 +184,7 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -373,6 +374,7 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -563,6 +565,7 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -785,6 +788,7 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -942,6 +946,7 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -1143,6 +1148,7 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -1392,6 +1398,7 @@ fn resolve_index_url() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -1651,6 +1658,7 @@ fn resolve_index_url() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -1865,6 +1873,7 @@ fn resolve_find_links() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -2044,6 +2053,7 @@ fn resolve_top_level() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -2283,6 +2293,7 @@ fn resolve_top_level() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -2505,6 +2516,7 @@ fn resolve_top_level() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -2683,6 +2695,7 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -2845,6 +2858,7 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -3007,6 +3021,7 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -3171,6 +3186,7 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -3327,6 +3343,7 @@ fn resolve_tool() -> anyhow::Result<()> {
             config_settings_package: None,
             no_build_isolation: None,
             no_build_isolation_package: None,
+            extra_build_dependencies: None,
             exclude_newer: None,
             link_mode: Some(
                 Clone,
@@ -3369,6 +3386,7 @@ fn resolve_tool() -> anyhow::Result<()> {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: LowestDirect,
                 sources: Enabled,
@@ -3527,6 +3545,7 @@ fn resolve_poetry_toml() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -3757,6 +3776,7 @@ fn resolve_both() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -3991,6 +4011,7 @@ fn resolve_both_special_fields() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -4304,6 +4325,7 @@ fn resolve_config_file() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -4384,7 +4406,7 @@ fn resolve_config_file() -> anyhow::Result<()> {
       |
     1 | [project]
       |  ^^^^^^^
-    unknown field `project`, expected one of `required-version`, `native-tls`, `offline`, `no-cache`, `cache-dir`, `preview`, `python-preference`, `python-downloads`, `concurrent-downloads`, `concurrent-builds`, `concurrent-installs`, `index`, `index-url`, `extra-index-url`, `no-index`, `find-links`, `index-strategy`, `keyring-provider`, `allow-insecure-host`, `resolution`, `prerelease`, `fork-strategy`, `dependency-metadata`, `config-settings`, `config-settings-package`, `no-build-isolation`, `no-build-isolation-package`, `exclude-newer`, `link-mode`, `compile-bytecode`, `no-sources`, `upgrade`, `upgrade-package`, `reinstall`, `reinstall-package`, `no-build`, `no-build-package`, `no-binary`, `no-binary-package`, `python-install-mirror`, `pypy-install-mirror`, `python-downloads-json-url`, `publish-url`, `trusted-publishing`, `check-url`, `add-bounds`, `pip`, `cache-keys`, `override-dependencies`, `constraint-dependencies`, `build-constraint-dependencies`, `environments`, `required-environments`, `conflicts`, `workspace`, `sources`, `managed`, `package`, `default-groups`, `dependency-groups`, `dev-dependencies`, `build-backend`
+    unknown field `project`, expected one of `required-version`, `native-tls`, `offline`, `no-cache`, `cache-dir`, `preview`, `python-preference`, `python-downloads`, `concurrent-downloads`, `concurrent-builds`, `concurrent-installs`, `index`, `index-url`, `extra-index-url`, `no-index`, `find-links`, `index-strategy`, `keyring-provider`, `allow-insecure-host`, `resolution`, `prerelease`, `fork-strategy`, `dependency-metadata`, `config-settings`, `config-settings-package`, `no-build-isolation`, `no-build-isolation-package`, `extra-build-dependencies`, `exclude-newer`, `link-mode`, `compile-bytecode`, `no-sources`, `upgrade`, `upgrade-package`, `reinstall`, `reinstall-package`, `no-build`, `no-build-package`, `no-binary`, `no-binary-package`, `python-install-mirror`, `pypy-install-mirror`, `python-downloads-json-url`, `publish-url`, `trusted-publishing`, `check-url`, `add-bounds`, `pip`, `cache-keys`, `override-dependencies`, `constraint-dependencies`, `build-constraint-dependencies`, `environments`, `required-environments`, `conflicts`, `workspace`, `sources`, `managed`, `package`, `default-groups`, `dependency-groups`, `dev-dependencies`, `build-backend`
     "
     );
 
@@ -4559,6 +4581,7 @@ fn resolve_skip_empty() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -4724,6 +4747,7 @@ fn resolve_skip_empty() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -4908,6 +4932,7 @@ fn allow_insecure_host() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -5153,6 +5178,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -5377,6 +5403,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -5607,6 +5634,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -5832,6 +5860,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6064,6 +6093,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6289,6 +6319,7 @@ fn index_priority() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6458,6 +6489,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6613,6 +6645,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6766,6 +6799,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -6921,6 +6955,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -7074,6 +7109,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -7228,6 +7264,7 @@ fn verify_hashes() -> anyhow::Result<()> {
             torch_backend: None,
             no_build_isolation: false,
             no_build_isolation_package: [],
+            extra_build_dependencies: {},
             build_options: BuildOptions {
                 no_binary: None,
                 no_build: None,
@@ -7320,7 +7357,7 @@ fn preview_features() {
         show_settings: true,
         preview: Preview {
             flags: PreviewFeatures(
-                PYTHON_INSTALL_DEFAULT | PYTHON_UPGRADE | JSON_OUTPUT | PYLOCK | ADD_BOUNDS,
+                PYTHON_INSTALL_DEFAULT | PYTHON_UPGRADE | JSON_OUTPUT | PYLOCK | ADD_BOUNDS | EXTRA_BUILD_DEPENDENCIES,
             ),
         },
         python_preference: Managed,
@@ -7386,6 +7423,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
@@ -7488,6 +7526,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
@@ -7524,7 +7563,7 @@ fn preview_features() {
         show_settings: true,
         preview: Preview {
             flags: PreviewFeatures(
-                PYTHON_INSTALL_DEFAULT | PYTHON_UPGRADE | JSON_OUTPUT | PYLOCK | ADD_BOUNDS,
+                PYTHON_INSTALL_DEFAULT | PYTHON_UPGRADE | JSON_OUTPUT | PYLOCK | ADD_BOUNDS | EXTRA_BUILD_DEPENDENCIES,
             ),
         },
         python_preference: Managed,
@@ -7590,6 +7629,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
@@ -7692,6 +7732,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
@@ -7794,6 +7835,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
@@ -7898,6 +7940,7 @@ fn preview_features() {
                 link_mode: Clone,
                 no_build_isolation: false,
                 no_build_isolation_package: [],
+                extra_build_dependencies: {},
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
diff --git a/crates/uv/tests/it/sync.rs b/crates/uv/tests/it/sync.rs
index 3bade6dea..a7620df92 100644
--- a/crates/uv/tests/it/sync.rs
+++ b/crates/uv/tests/it/sync.rs
@@ -1567,6 +1567,401 @@ fn sync_build_isolation_extra() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn sync_extra_build_dependencies() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_counts();
+
+    // Write a test package that arbitrarily requires `anyio` at build time
+    let child = context.temp_dir.child("child");
+    child.create_dir_all()?;
+    let child_pyproject_toml = child.child("pyproject.toml");
+    child_pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+    "#})?;
+    let build_backend = child.child("build_backend.py");
+    build_backend.write_str(indoc! {r#"
+        import sys
+
+        from hatchling.build import *
+
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            print("Missing `anyio` module", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    child.child("src/child/__init__.py").touch()?;
+
+    let parent = &context.temp_dir;
+    let pyproject_toml = parent.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        dependencies = ["child"]
+
+        [tool.uv.sources]
+        child = { path = "child" }
+    "#})?;
+
+    context.venv().arg("--clear").assert().success();
+    // Running `uv sync` should fail due to missing build-dependencies
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved [N] packages in [TIME]
+      × Failed to build `child @ file://[TEMP_DIR]/child`
+      ├─▶ The build backend returned an error
+      ╰─▶ Call to `build_backend.build_wheel` failed (exit status: 1)
+
+          [stderr]
+          Missing `anyio` module
+
+          hint: This usually indicates a problem with the package or the build environment.
+      help: `child` was included because `parent` (v0.1.0) depends on `child`
+    ");
+
+    // Adding `extra-build-dependencies` should solve the issue
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        dependencies = ["child"]
+
+        [tool.uv.sources]
+        child = { path = "child" }
+
+        [tool.uv.extra-build-dependencies]
+        child = ["anyio"]
+    "#})?;
+
+    context.venv().arg("--clear").assert().success();
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+    ");
+
+    // Adding `extra-build-dependencies` with the wrong name should fail the build
+    // (the cache is invalidated when extra build dependencies change)
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        dependencies = ["child"]
+
+        [tool.uv.sources]
+        child = { path = "child" }
+
+        [tool.uv.extra-build-dependencies]
+        wrong_name = ["anyio"]
+    "#})?;
+
+    context.venv().arg("--clear").assert().success();
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+      × Failed to build `child @ file://[TEMP_DIR]/child`
+      ├─▶ The build backend returned an error
+      ╰─▶ Call to `build_backend.build_wheel` failed (exit status: 1)
+
+          [stderr]
+          Missing `anyio` module
+
+          hint: This usually indicates a problem with the package or the build environment.
+      help: `child` was included because `parent` (v0.1.0) depends on `child`
+    ");
+
+    // Write a test package that arbitrarily bans `anyio` at build time
+    let bad_child = context.temp_dir.child("bad_child");
+    bad_child.create_dir_all()?;
+    let bad_child_pyproject_toml = bad_child.child("pyproject.toml");
+    bad_child_pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "bad_child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+    "#})?;
+    let build_backend = bad_child.child("build_backend.py");
+    build_backend.write_str(indoc! {r#"
+        import sys
+
+        from hatchling.build import *
+
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            pass
+        else:
+            print("Found `anyio` module", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    bad_child.child("src/bad_child/__init__.py").touch()?;
+
+    // Depend on `bad_child` too
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        dependencies = ["child", "bad_child"]
+
+        [tool.uv.sources]
+        child = { path = "child" }
+        bad_child = { path = "bad_child" }
+
+        [tool.uv.extra-build-dependencies]
+        child = ["anyio"]
+        bad_child = ["anyio"]
+    "#})?;
+
+    // Confirm that `bad_child` fails if anyio is provided
+    context.venv().arg("--clear").assert().success();
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+      × Failed to build `bad-child @ file://[TEMP_DIR]/bad_child`
+      ├─▶ The build backend returned an error
+      ╰─▶ Call to `build_backend.build_wheel` failed (exit status: 1)
+
+          [stderr]
+          Found `anyio` module
+
+          hint: This usually indicates a problem with the package or the build environment.
+      help: `bad-child` was included because `parent` (v0.1.0) depends on `bad-child`
+    ");
+
+    // But `anyio` is not provided to `bad_child` if scoped to `child`
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        dependencies = ["child", "bad_child"]
+
+        [tool.uv.sources]
+        child = { path = "child" }
+        bad_child = { path = "bad_child" }
+
+        [tool.uv.extra-build-dependencies]
+        child = ["anyio"]
+    "#})?;
+
+    context.venv().arg("--clear").assert().success();
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + bad-child==0.1.0 (from file://[TEMP_DIR]/bad_child)
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn sync_extra_build_dependencies_sources() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_counts();
+
+    let anyio_local = context.workspace_root.join("scripts/packages/anyio_local");
+
+    // Write a test package that arbitrarily requires `anyio` at a specific _path_ at build time
+    let child = context.temp_dir.child("child");
+    child.create_dir_all()?;
+    let child_pyproject_toml = child.child("pyproject.toml");
+    child_pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+    "#})?;
+    let build_backend = child.child("build_backend.py");
+    build_backend.write_str(&formatdoc! {r#"
+        import sys
+
+        from hatchling.build import *
+
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            print("Missing `anyio` module", file=sys.stderr)
+            sys.exit(1)
+
+        # Check that we got the local version of anyio by checking for the marker
+        if not hasattr(anyio, 'LOCAL_ANYIO_MARKER'):
+            print("Found system anyio instead of local anyio", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    child.child("src/child/__init__.py").touch()?;
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(&formatdoc! {r#"
+            [project]
+            name = "project"
+            version = "0.1.0"
+            requires-python = ">=3.12"
+            dependencies = ["child"]
+
+            [tool.uv.sources]
+            anyio = {{ path = "{anyio_local}" }}
+            child = {{ path = "child" }}
+
+            [tool.uv.extra-build-dependencies]
+            child = ["anyio"]
+        "#,
+        anyio_local = anyio_local.portable_display(),
+    })?;
+
+    // Running `uv sync` should succeed, as `anyio` is provided as a source
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+    ");
+
+    // TODO(zanieb): We want to test with `--no-sources` too but unfortunately that's not easy
+    // because it'll disable the `child` path source too!
+
+    Ok(())
+}
+
+#[test]
+fn sync_extra_build_dependencies_sources_from_child() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_counts();
+
+    let anyio_local = context.workspace_root.join("scripts/packages/anyio_local");
+
+    // Write a test package that arbitrarily requires `anyio` at a specific _path_ at build time
+    let child = context.temp_dir.child("child");
+    child.create_dir_all()?;
+    let child_pyproject_toml = child.child("pyproject.toml");
+    child_pyproject_toml.write_str(&formatdoc! {r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+
+        [tool.uv.sources]
+        anyio = {{ path = "{}" }}
+    "#, anyio_local.portable_display()
+    })?;
+    let build_backend = child.child("build_backend.py");
+    build_backend.write_str(&formatdoc! {r#"
+        import sys
+
+        from hatchling.build import *
+
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            print("Missing `anyio` module", file=sys.stderr)
+            sys.exit(1)
+
+        # Check that we got the local version of anyio by checking for the marker
+        if not hasattr(anyio, 'LOCAL_ANYIO_MARKER'):
+            print("Found system anyio instead of local anyio", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    child.child("src/child/__init__.py").touch()?;
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+            [project]
+            name = "project"
+            version = "0.1.0"
+            requires-python = ">=3.12"
+            dependencies = ["child"]
+
+            [tool.uv.sources]
+            child = { path = "child" }
+
+            [tool.uv.extra-build-dependencies]
+            child = ["anyio"]
+        "#,
+    })?;
+
+    // Running `uv sync` should fail due to the unapplied source
+    uv_snapshot!(context.filters(), context.sync().arg("--reinstall").arg("--refresh"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: The `extra-build-dependencies` option is experimental and may change without warning. Pass `--preview-features extra-build-dependencies` to disable this warning.
+    Resolved [N] packages in [TIME]
+      × Failed to build `child @ file://[TEMP_DIR]/child`
+      ├─▶ The build backend returned an error
+      ╰─▶ Call to `build_backend.build_wheel` failed (exit status: 1)
+
+          [stderr]
+          Found system anyio instead of local anyio
+
+          hint: This usually indicates a problem with the package or the build environment.
+      help: `child` was included because `project` (v0.1.0) depends on `child`
+    ");
+
+    Ok(())
+}
+
 /// Avoid using incompatible versions for build dependencies that are also part of the resolved
 /// environment. This is a very subtle issue, but: when locking, we don't enforce platform
 /// compatibility. So, if we reuse the resolver state to install, and the install itself has to
@@ -4198,6 +4593,187 @@ fn no_install_project_no_build() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn sync_extra_build_dependencies_script() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_counts();
+
+    // Write a test package that arbitrarily requires `anyio` at build time
+    let child = context.temp_dir.child("child");
+    child.create_dir_all()?;
+    let child_pyproject_toml = child.child("pyproject.toml");
+    child_pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+    "#})?;
+    let build_backend = child.child("build_backend.py");
+    build_backend.write_str(indoc! {r#"
+        import sys
+        from hatchling.build import *
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            print("Missing `anyio` module", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    child.child("src/child/__init__.py").touch()?;
+
+    // Create a script that depends on the child package
+    let script = context.temp_dir.child("script.py");
+    script.write_str(indoc! {r#"
+        # /// script
+        # requires-python = ">=3.12"
+        # dependencies = ["child"]
+        #
+        # [tool.uv.sources]
+        # child = { path = "child" }
+        # ///
+    "#})?;
+
+    let filters = context
+        .filters()
+        .into_iter()
+        .chain(vec![(
+            r"environments-v2/script-[a-z0-9]+",
+            "environments-v2/script-[HASH]",
+        )])
+        .collect::<Vec<_>>();
+
+    // Running `uv sync` should fail due to missing build-dependencies
+    uv_snapshot!(filters, context.sync().arg("--script").arg("script.py"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Creating script environment at: [CACHE_DIR]/environments-v2/script-[HASH]
+    Resolved [N] packages in [TIME]
+      × Failed to build `child @ file://[TEMP_DIR]/child`
+      ├─▶ The build backend returned an error
+      ╰─▶ Call to `build_backend.build_wheel` failed (exit status: 1)
+
+          [stderr]
+          Missing `anyio` module
+
+          hint: This usually indicates a problem with the package or the build environment.
+    ");
+
+    // Add extra build dependencies to the script
+    script.write_str(indoc! {r#"
+        # /// script
+        # requires-python = ">=3.12"
+        # dependencies = ["child"]
+        #
+        # [tool.uv.sources]
+        # child = { path = "child" }
+        #
+        # [tool.uv.extra-build-dependencies]
+        # child = ["anyio"]
+        # ///
+    "#})?;
+
+    // Running `uv sync` should now succeed due to extra build-dependencies
+    context.venv().arg("--clear").assert().success();
+    uv_snapshot!(filters, context.sync().arg("--script").arg("script.py"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using script environment at: [CACHE_DIR]/environments-v2/script-[HASH]
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn sync_extra_build_dependencies_script_sources() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_counts();
+    let anyio_local = context.workspace_root.join("scripts/packages/anyio_local");
+
+    // Write a test package that arbitrarily requires `anyio` at a specific _path_ at build time
+    let child = context.temp_dir.child("child");
+    child.create_dir_all()?;
+    let child_pyproject_toml = child.child("pyproject.toml");
+    child_pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.9"
+        [build-system]
+        requires = ["hatchling"]
+        backend-path = ["."]
+        build-backend = "build_backend"
+    "#})?;
+    let build_backend = child.child("build_backend.py");
+    build_backend.write_str(&formatdoc! {r#"
+        import sys
+        from hatchling.build import *
+        try:
+            import anyio
+        except ModuleNotFoundError:
+            print("Missing `anyio` module", file=sys.stderr)
+            sys.exit(1)
+
+        # Check that we got the local version of anyio by checking for the marker
+        if not hasattr(anyio, 'LOCAL_ANYIO_MARKER'):
+            print("Found system anyio instead of local anyio", file=sys.stderr)
+            sys.exit(1)
+    "#})?;
+    child.child("src/child/__init__.py").touch()?;
+
+    // Create a script that depends on the child package
+    let script = context.temp_dir.child("script.py");
+    script.write_str(&formatdoc! {r#"
+        # /// script
+        # requires-python = ">=3.12"
+        # dependencies = ["child"]
+        #
+        # [tool.uv.sources]
+        # anyio = {{ path = "{}" }}
+        # child = {{ path = "child" }}
+        #
+        # [tool.uv.extra-build-dependencies]
+        # child = ["anyio"]
+        # ///
+    "#, anyio_local.portable_display()
+    })?;
+
+    let filters = context
+        .filters()
+        .into_iter()
+        .chain(vec![(
+            r"environments-v2/script-[a-z0-9]+",
+            "environments-v2/script-[HASH]",
+        )])
+        .collect::<Vec<_>>();
+
+    // Running `uv sync` should succeed with the sources applied
+    uv_snapshot!(filters, context.sync().arg("--script").arg("script.py"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Creating script environment at: [CACHE_DIR]/environments-v2/script-[HASH]
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+    ");
+
+    Ok(())
+}
+
 #[test]
 fn virtual_no_build() -> Result<()> {
     let context = TestContext::new("3.12");
diff --git a/docs/reference/settings.md b/docs/reference/settings.md
index 31dd1157b..dbf6644af 100644
--- a/docs/reference/settings.md
+++ b/docs/reference/settings.md
@@ -202,6 +202,28 @@ environments = ["sys_platform == 'darwin'"]
 
 ---
 
+### [`extra-build-dependencies`](#extra-build-dependencies) {: #extra-build-dependencies }
+
+Additional build dependencies for packages.
+
+This allows extending the PEP 517 build environment for the project's dependencies with
+additional packages. This is useful for packages that assume the presence of packages, like,
+`pip`, and do not declare them as build dependencies.
+
+**Default value**: `[]`
+
+**Type**: `dict`
+
+**Example usage**:
+
+```toml title="pyproject.toml"
+
+[tool.uv.extra-build-dependencies]
+pytest = ["pip"]
+```
+
+---
+
 ### [`index`](#index) {: #index }
 
 The indexes to use when resolving dependencies.
@@ -1135,6 +1157,36 @@ behave consistently across timezones.
 
 ---
 
+### [`extra-build-dependencies`](#extra-build-dependencies) {: #extra-build-dependencies }
+
+Additional build dependencies for packages.
+
+This allows extending the PEP 517 build environment for the project's dependencies with
+additional packages. This is useful for packages that assume the presence of packages, like,
+`pip`, and do not declare them as build dependencies.
+
+**Default value**: `[]`
+
+**Type**: `dict`
+
+**Example usage**:
+
+=== "pyproject.toml"
+
+    ```toml
+    [tool.uv]
+    [extra-build-dependencies] 
+    pytest = ["setuptools"]
+    ```
+=== "uv.toml"
+
+    ```toml
+    [extra-build-dependencies] 
+    pytest = ["setuptools"]
+    ```
+
+---
+
 ### [`extra-index-url`](#extra-index-url) {: #extra-index-url }
 
 Extra URLs of package indexes to use, in addition to `--index-url`.
@@ -2596,6 +2648,38 @@ Only applies to `pyproject.toml`, `setup.py`, and `setup.cfg` sources.
 
 ---
 
+#### [`extra-build-dependencies`](#pip_extra-build-dependencies) {: #pip_extra-build-dependencies }
+<span id="extra-build-dependencies"></span>
+
+Additional build dependencies for packages.
+
+This allows extending the PEP 517 build environment for the project's dependencies with
+additional packages. This is useful for packages that assume the presence of packages, like,
+`pip`, and do not declare them as build dependencies.
+
+**Default value**: `[]`
+
+**Type**: `dict`
+
+**Example usage**:
+
+=== "pyproject.toml"
+
+    ```toml
+    [tool.uv.pip]
+    [extra-build-dependencies]
+    pytest = ["setuptools"]
+    ```
+=== "uv.toml"
+
+    ```toml
+    [pip]
+    [extra-build-dependencies]
+    pytest = ["setuptools"]
+    ```
+
+---
+
 #### [`extra-index-url`](#pip_extra-index-url) {: #pip_extra-index-url }
 <span id="extra-index-url"></span>
 
diff --git a/scripts/packages/anyio_local/anyio/__init__.py b/scripts/packages/anyio_local/anyio/__init__.py
index e69de29bb..a3e374663 100644
--- a/scripts/packages/anyio_local/anyio/__init__.py
+++ b/scripts/packages/anyio_local/anyio/__init__.py
@@ -0,0 +1,2 @@
+# This is a local dummy anyio package
+LOCAL_ANYIO_MARKER = True
\ No newline at end of file
diff --git a/uv.schema.json b/uv.schema.json
index d592eca73..81daff6f4 100644
--- a/uv.schema.json
+++ b/uv.schema.json
@@ -225,6 +225,17 @@
         }
       ]
     },
+    "extra-build-dependencies": {
+      "description": "Additional build dependencies for packages.\n\nThis allows extending the PEP 517 build environment for the project's dependencies with\nadditional packages. This is useful for packages that assume the presence of packages, like,\n`pip`, and do not declare them as build dependencies.",
+      "anyOf": [
+        {
+          "$ref": "#/definitions/ToolUvExtraBuildDependencies"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
     "extra-index-url": {
       "description": "Extra URLs of package indexes to use, in addition to `--index-url`.\n\nAccepts either a repository compliant with [PEP 503](https://peps.python.org/pep-0503/)\n(the simple repository API), or a local directory laid out in the same format.\n\nAll indexes provided via this flag take priority over the index specified by\n[`index_url`](#index-url) or [`index`](#index) with `default = true`. When multiple indexes\nare provided, earlier values take priority.\n\nTo control uv's resolution strategy when multiple indexes are present, see\n[`index_strategy`](#index-strategy).\n\n(Deprecated: use `index` instead.)",
       "type": [
@@ -1312,6 +1323,19 @@
             "$ref": "#/definitions/ExtraName"
           }
         },
+        "extra-build-dependencies": {
+          "description": "Additional build dependencies for packages.\n\nThis allows extending the PEP 517 build environment for the project's dependencies with\nadditional packages. This is useful for packages that assume the presence of packages, like,\n`pip`, and do not declare them as build dependencies.",
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": {
+            "type": "array",
+            "items": {
+              "$ref": "#/definitions/Requirement"
+            }
+          }
+        },
         "extra-index-url": {
           "description": "Extra URLs of package indexes to use, in addition to `--index-url`.\n\nAccepts either a repository compliant with [PEP 503](https://peps.python.org/pep-0503/)\n(the simple repository API), or a local directory laid out in the same format.\n\nAll indexes provided via this flag take priority over the index specified by\n[`index_url`](#index-url). When multiple indexes are provided, earlier values take priority.\n\nTo control uv's resolution strategy when multiple indexes are present, see\n[`index_strategy`](#index-strategy).",
           "type": [
@@ -2341,6 +2365,15 @@
         "$ref": "#/definitions/DependencyGroupSettings"
       }
     },
+    "ToolUvExtraBuildDependencies": {
+      "type": "object",
+      "additionalProperties": {
+        "type": "array",
+        "items": {
+          "$ref": "#/definitions/Requirement"
+        }
+      }
+    },
     "ToolUvSources": {
       "type": "object",
       "additionalProperties": {