diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BazelRuleAnalysisThreadContext.java b/src/main/java/com/google/devtools/build/lib/analysis/BazelRuleAnalysisThreadContext.java
index 21767620d49135..ff214d1ab79e57 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BazelRuleAnalysisThreadContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BazelRuleAnalysisThreadContext.java
@@ -14,8 +14,8 @@
 
 package com.google.devtools.build.lib.analysis;
 
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import javax.annotation.Nullable;
 import net.starlark.java.eval.EvalException;
@@ -33,7 +33,7 @@ public class BazelRuleAnalysisThreadContext extends BazelStarlarkContext {
    * @param ruleContext is the {@link RuleContext} of the rule for analysis of a rule or aspect
    */
   public BazelRuleAnalysisThreadContext(RuleContext ruleContext) {
-    super(Phase.ANALYSIS);
+    super(Phase.ANALYSIS, ruleContext.getAnalysisEnvironment()::getMainRepoMapping);
     this.ruleContext = ruleContext;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/StarlarkDefinedConfigTransition.java b/src/main/java/com/google/devtools/build/lib/analysis/config/StarlarkDefinedConfigTransition.java
index 77c39d9f1800f0..fd66a756039879 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/StarlarkDefinedConfigTransition.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/StarlarkDefinedConfigTransition.java
@@ -37,8 +37,8 @@
 import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext.Phase;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext.Phase;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.RuleTransitionData;
 import com.google.devtools.build.lib.packages.StructImpl;
@@ -552,7 +552,7 @@ public ImmutableMap<String, Map<String, Object>> evaluate(
         // Create a new {@link BazelStarlarkContext} for the new thread. We need to
         // create a new context every time because {@link BazelStarlarkContext}s
         // should be confined to a single thread.
-        new BazelStarlarkContext(Phase.ANALYSIS).storeInThread(thread);
+        new BazelStarlarkContext(Phase.ANALYSIS, /* mainRepoMapping= */ null).storeInThread(thread);
 
         result =
             Starlark.fastcall(
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
index 89d68af5108081..9eeb2d26b0eeea 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
@@ -64,7 +64,7 @@
 import com.google.devtools.build.lib.packages.Attribute.StarlarkComputedDefaultTemplate;
 import com.google.devtools.build.lib.packages.AttributeTransitionData;
 import com.google.devtools.build.lib.packages.AttributeValueSource;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.packages.BuildSetting;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.BuiltinRestriction;
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
index 93c1046c98d2b6..f7fa1be8c70b57 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
@@ -34,6 +34,8 @@
 import com.google.devtools.build.lib.bazel.repository.downloader.DownloadManager;
 import com.google.devtools.build.lib.bazel.repository.starlark.StarlarkRepositoryModule.RepositoryRuleFunction;
 import com.google.devtools.build.lib.cmdline.BazelModuleContext;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext.Phase;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
@@ -132,6 +134,12 @@ public SkyValue compute(SkyKey skyKey, Environment env)
     if (starlarkSemantics == null) {
       return null;
     }
+    RepositoryMappingValue mainRepoMappingValue =
+        (RepositoryMappingValue)
+            env.getValue(RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS);
+    if (mainRepoMappingValue == null) {
+      return null;
+    }
 
     ModuleExtensionId extensionId = (ModuleExtensionId) skyKey.argument();
     SingleExtensionUsagesValue usagesValue =
@@ -182,7 +190,12 @@ public SkyValue compute(SkyKey skyKey, Environment env)
     // Run that extension!
     env.getListener().post(ModuleExtensionEvaluationProgress.ongoing(extensionId, "starting"));
     RunModuleExtensionResult moduleExtensionResult =
-        extension.run(env, usagesValue, starlarkSemantics, extensionId);
+        extension.run(
+            env,
+            usagesValue,
+            starlarkSemantics,
+            extensionId,
+            mainRepoMappingValue.getRepositoryMapping());
     if (moduleExtensionResult == null) {
       return null;
     }
@@ -525,7 +538,8 @@ RunModuleExtensionResult run(
         Environment env,
         SingleExtensionUsagesValue usagesValue,
         StarlarkSemantics starlarkSemantics,
-        ModuleExtensionId extensionId)
+        ModuleExtensionId extensionId,
+        RepositoryMapping repositoryMapping)
         throws InterruptedException, SingleExtensionEvalFunctionException;
   }
 
@@ -677,7 +691,8 @@ public RunModuleExtensionResult run(
         Environment env,
         SingleExtensionUsagesValue usagesValue,
         StarlarkSemantics starlarkSemantics,
-        ModuleExtensionId extensionId)
+        ModuleExtensionId extensionId,
+        RepositoryMapping mainRepositoryMapping)
         throws InterruptedException, SingleExtensionEvalFunctionException {
       var generatedRepoSpecs = ImmutableMap.<String, RepoSpec>builderWithExpectedSize(repos.size());
       // Instantiate the repos one by one.
@@ -846,7 +861,8 @@ public RunModuleExtensionResult run(
         Environment env,
         SingleExtensionUsagesValue usagesValue,
         StarlarkSemantics starlarkSemantics,
-        ModuleExtensionId extensionId)
+        ModuleExtensionId extensionId,
+        RepositoryMapping mainRepositoryMapping)
         throws InterruptedException, SingleExtensionEvalFunctionException {
       ModuleExtensionEvalStarlarkThreadContext threadContext =
           new ModuleExtensionEvalStarlarkThreadContext(
@@ -870,6 +886,8 @@ public RunModuleExtensionResult run(
         thread.setPrintHandler(Event.makeDebugPrintHandler(env.getListener()));
         moduleContext = createContext(env, usagesValue, starlarkSemantics, extensionId);
         threadContext.storeInThread(thread);
+        new BazelStarlarkContext(Phase.WORKSPACE, () -> mainRepositoryMapping)
+            .storeInThread(thread);
         // This is used by the `Label()` constructor in Starlark, to record any attempts to resolve
         // apparent repo names to canonical repo names. See #20721 for why this is necessary.
         thread.setThreadLocal(Label.RepoMappingRecorder.class, repoMappingRecorder);
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/BUILD b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/BUILD
index bbc23ef10fe95f..ec879778d6d0b1 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/BUILD
@@ -46,6 +46,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/skyframe:directory_tree_digest_value",
         "//src/main/java/com/google/devtools/build/lib/skyframe:ignored_package_prefixes_value",
         "//src/main/java/com/google/devtools/build/lib/skyframe:precomputed_value",
+        "//src/main/java/com/google/devtools/build/lib/skyframe:repository_mapping_value",
         "//src/main/java/com/google/devtools/build/lib/starlarkbuildapi/repository",
         "//src/main/java/com/google/devtools/build/lib/util",
         "//src/main/java/com/google/devtools/build/lib/util:string",
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryFunction.java
index 63545a9f3e0fa9..8cfa984c43c13d 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryFunction.java
@@ -25,11 +25,12 @@
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.bazel.repository.RepositoryResolvedEvent;
 import com.google.devtools.build.lib.bazel.repository.downloader.DownloadManager;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
 import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
@@ -46,6 +47,7 @@
 import com.google.devtools.build.lib.runtime.RepositoryRemoteExecutor;
 import com.google.devtools.build.lib.skyframe.IgnoredPackagePrefixesValue;
 import com.google.devtools.build.lib.skyframe.PrecomputedValue;
+import com.google.devtools.build.lib.skyframe.RepositoryMappingValue;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -242,6 +244,20 @@ private RepositoryDirectoryValue.Builder fetchInternal(
       return null;
     }
 
+    boolean enableBzlmod = starlarkSemantics.getBool(BuildLanguageOptions.ENABLE_BZLMOD);
+    RepositoryMapping mainRepoMapping;
+    if (enableBzlmod || !isWorkspaceRepo(rule)) {
+      var mainRepoMappingValue =
+          (RepositoryMappingValue)
+              env.getValue(RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS);
+      if (mainRepoMappingValue == null) {
+        return null;
+      }
+      mainRepoMapping = mainRepoMappingValue.getRepositoryMapping();
+    } else {
+      mainRepoMapping = rule.getPackage().getRepositoryMapping();
+    }
+
     IgnoredPackagePrefixesValue ignoredPackagesValue =
         (IgnoredPackagePrefixesValue) env.getValue(IgnoredPackagePrefixesValue.key());
     if (env.valuesMissing()) {
@@ -264,7 +280,8 @@ private RepositoryDirectoryValue.Builder fetchInternal(
         thread.setThreadLocal(Label.RepoMappingRecorder.class, repoMappingRecorder);
       }
 
-      new BazelStarlarkContext(BazelStarlarkContext.Phase.LOADING).storeInThread(thread); // "fetch"
+      new BazelStarlarkContext(BazelStarlarkContext.Phase.LOADING, () -> mainRepoMapping)
+          .storeInThread(thread); // "fetch"
 
       StarlarkRepositoryContext starlarkRepositoryContext =
           new StarlarkRepositoryContext(
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryModule.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryModule.java
index 4c43f17b824358..237d2164971131 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryModule.java
@@ -33,7 +33,7 @@
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.AttributeValueSource;
-import com.google.devtools.build.lib.packages.BazelStarlarkContext;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.packages.BzlInitThreadContext;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.packages.RuleClass;
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
index 89ab67d81d099f..87ab69d0557309 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
@@ -17,6 +17,7 @@ java_library(
     srcs = [
         "BazelCompileContext.java",
         "BazelModuleContext.java",
+        "BazelStarlarkContext.java",
         "Label.java",
         "LabelCodec.java",
         "LabelConstants.java",
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/BazelModuleContext.java b/src/main/java/com/google/devtools/build/lib/cmdline/BazelModuleContext.java
index 8c136c43dddf13..2fa9e1c6fb1634 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/BazelModuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/BazelModuleContext.java
@@ -44,13 +44,6 @@ public abstract class BazelModuleContext {
   /** The repository mapping applicable to the repo where the .bzl file is located in. */
   public abstract RepositoryMapping repoMapping();
 
-  /**
-   * The repository mapping applicable to the main repository. This is purely meant to support
-   * {@link Label#debugPrint}.
-   */
-  @Nullable
-  public abstract RepositoryMapping mainRepoMapping();
-
   /** Returns the name of the module's .bzl file, as provided to the parser. */
   public abstract String filename();
 
@@ -167,12 +160,11 @@ public static BazelModuleContext ofInnermostBzlOrFail(StarlarkThread thread, Str
   public static BazelModuleContext create(
       Label label,
       RepositoryMapping repoMapping,
-      @Nullable RepositoryMapping mainRepoMapping,
       String filename,
       ImmutableList<Module> loads,
       byte[] bzlTransitiveDigest) {
     return new AutoValue_BazelModuleContext(
-        label, repoMapping, mainRepoMapping, filename, loads, bzlTransitiveDigest);
+        label, repoMapping, filename, loads, bzlTransitiveDigest);
   }
 
   public final Label.PackageContext packageContext() {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BazelStarlarkContext.java b/src/main/java/com/google/devtools/build/lib/cmdline/BazelStarlarkContext.java
similarity index 90%
rename from src/main/java/com/google/devtools/build/lib/packages/BazelStarlarkContext.java
rename to src/main/java/com/google/devtools/build/lib/cmdline/BazelStarlarkContext.java
index 325628b4c408a3..d9dcd10fa583ed 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BazelStarlarkContext.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/BazelStarlarkContext.java
@@ -11,9 +11,11 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-package com.google.devtools.build.lib.packages;
+package com.google.devtools.build.lib.cmdline;
 
 import com.google.common.base.Preconditions;
+import com.google.devtools.build.lib.supplier.InterruptibleSupplier;
+import javax.annotation.Nullable;
 import net.starlark.java.eval.EvalException;
 import net.starlark.java.eval.Starlark;
 import net.starlark.java.eval.StarlarkThread;
@@ -94,12 +96,15 @@ public void storeInThread(StarlarkThread thread) {
 
   // TODO(b/236456122): Eliminate Phase, migrate analysisRuleLabel to a separate context class.
   private final Phase phase;
+  @Nullable private final InterruptibleSupplier<RepositoryMapping> mainRepoMappingSupplier;
 
   /**
    * @param phase the phase to which this Starlark thread belongs
    */
-  public BazelStarlarkContext(Phase phase) {
+  public BazelStarlarkContext(
+      Phase phase, @Nullable InterruptibleSupplier<RepositoryMapping> mainRepoMappingSupplier) {
     this.phase = Preconditions.checkNotNull(phase);
+    this.mainRepoMappingSupplier = mainRepoMappingSupplier;
   }
 
   /** Returns the phase associated with this context. */
@@ -107,6 +112,15 @@ public Phase getPhase() {
     return phase;
   }
 
+  /**
+   * The repository mapping applicable to the main repository. This is purely meant to support
+   * {@link Label#debugPrint}.
+   */
+  @Nullable
+  public RepositoryMapping getMainRepoMapping() throws InterruptedException {
+    return mainRepoMappingSupplier == null ? null : mainRepoMappingSupplier.get();
+  }
+
   @Override
   public String getContextForUncheckedException() {
     return phase.toString();
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index 962f468888e8ce..5a819c743bebc6 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -661,7 +661,13 @@ public void repr(Printer printer) {
 
   @Override
   public void debugPrint(Printer printer, StarlarkThread thread) {
-    printer.append(getDisplayForm(BazelModuleContext.ofInnermostBzlOrThrow(thread).mainRepoMapping()));
+    RepositoryMapping mainRepoMapping;
+    try {
+      mainRepoMapping = BazelStarlarkContext.fromOrFail(thread).getMainRepoMapping();
+    } catch (EvalException | InterruptedException e) {
+      mainRepoMapping = null;
+    }
+    printer.append(getDisplayForm(mainRepoMapping));
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BuildGlobals.java b/src/main/java/com/google/devtools/build/lib/packages/BuildGlobals.java
index 2ae17ab4924e3c..eda38a5761e8c1 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BuildGlobals.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/BuildGlobals.java
@@ -15,6 +15,7 @@
 
 import com.google.devtools.build.docgen.annot.GlobalMethods;
 import com.google.devtools.build.docgen.annot.GlobalMethods.Environment;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.TargetDefinitionContext.NameConflictException;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BzlInitThreadContext.java b/src/main/java/com/google/devtools/build/lib/packages/BzlInitThreadContext.java
index 757f74278c442e..571a62c6eba233 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BzlInitThreadContext.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/BzlInitThreadContext.java
@@ -16,7 +16,9 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Optional;
@@ -57,15 +59,16 @@ public final class BzlInitThreadContext extends BazelStarlarkContext
    * @param networkAllowlistForTests an allowlist for rule classes created by this thread
    * @param fragmentNameToClass a map from configuration fragment name to configuration fragment
    *     class, such as "apple" to AppleConfiguration.class
-   * @param symbolGenerator symbol generator for this context
+   * @param mainRepoMapping the repository mapping of the main repository
    */
   public BzlInitThreadContext(
       Label bzlFile,
       byte[] transitiveDigest,
       RepositoryName toolsRepository,
       Optional<Label> networkAllowlistForTests,
-      ImmutableMap<String, Class<?>> fragmentNameToClass) {
-    super(BazelStarlarkContext.Phase.LOADING);
+      ImmutableMap<String, Class<?>> fragmentNameToClass,
+      RepositoryMapping mainRepoMapping) {
+    super(BazelStarlarkContext.Phase.LOADING, () -> mainRepoMapping);
     this.bzlFile = bzlFile;
     this.transitiveDigest = transitiveDigest;
     this.toolsRepository = toolsRepository;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Package.java b/src/main/java/com/google/devtools/build/lib/packages/Package.java
index b8de2b306c3514..391bc0efdc4748 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Package.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Package.java
@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.bugreport.BugReport;
 import com.google.devtools.build.lib.cmdline.BazelModuleContext;
 import com.google.devtools.build.lib.cmdline.BazelModuleContext.LoadGraphVisitor;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
@@ -758,6 +759,7 @@ public static Builder newPackageBuilder(
       Optional<String> associatedModuleVersion,
       boolean noImplicitFileExport,
       RepositoryMapping repositoryMapping,
+      RepositoryMapping mainRepositoryMapping,
       @Nullable Semaphore cpuBoundSemaphore,
       PackageOverheadEstimator packageOverheadEstimator,
       @Nullable ImmutableMap<Location, String> generatorMap,
@@ -775,6 +777,7 @@ public static Builder newPackageBuilder(
         associatedModuleVersion,
         noImplicitFileExport,
         repositoryMapping,
+        mainRepositoryMapping,
         cpuBoundSemaphore,
         packageOverheadEstimator,
         generatorMap,
@@ -802,6 +805,7 @@ public static Builder newExternalPackageBuilder(
         /* associatedModuleVersion= */ Optional.empty(),
         noImplicitFileExport,
         /* repositoryMapping= */ mainRepoMapping,
+        /* mainRepositoryMapping= */ mainRepoMapping,
         /* cpuBoundSemaphore= */ null,
         packageOverheadEstimator,
         /* generatorMap= */ null,
@@ -825,6 +829,7 @@ public static Builder newExternalPackageBuilderForBzlmod(
             /* associatedModuleVersion= */ Optional.empty(),
             noImplicitFileExport,
             repoMapping,
+            /* mainRepoMapping= */ null,
             /* cpuBoundSemaphore= */ null,
             PackageOverheadEstimator.NOOP_ESTIMATOR,
             /* generatorMap= */ null,
@@ -1062,7 +1067,7 @@ public T intern(T sample) {
     private boolean alreadyBuilt = false;
 
     private Builder(
-        BazelStarlarkContext.Phase phase,
+        Phase phase,
         SymbolGenerator<?> symbolGenerator,
         PackageSettings packageSettings,
         PackageIdentifier id,
@@ -1072,6 +1077,7 @@ private Builder(
         Optional<String> associatedModuleVersion,
         boolean noImplicitFileExport,
         RepositoryMapping repositoryMapping,
+        @Nullable RepositoryMapping mainRepositoryMapping,
         @Nullable Semaphore cpuBoundSemaphore,
         PackageOverheadEstimator packageOverheadEstimator,
         @Nullable ImmutableMap<Location, String> generatorMap,
@@ -1079,7 +1085,7 @@ private Builder(
         // Maybe convert null -> LEGACY_OFF, assuming that's the correct default.
         @Nullable ConfigSettingVisibilityPolicy configSettingVisibilityPolicy,
         @Nullable Globber globber) {
-      super(phase);
+      super(phase, mainRepositoryMapping);
       this.symbolGenerator = symbolGenerator;
 
       Metadata metadata = new Metadata();
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
index 3c78104b5d459b..d51353b382584d 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
@@ -234,6 +234,7 @@ public Package.Builder newPackageBuilder(
       Optional<String> associatedModuleVersion,
       StarlarkSemantics starlarkSemantics,
       RepositoryMapping repositoryMapping,
+      RepositoryMapping mainRepositoryMapping,
       @Nullable Semaphore cpuBoundSemaphore,
       @Nullable ImmutableMap<Location, String> generatorMap,
       @Nullable ConfigSettingVisibilityPolicy configSettingVisibilityPolicy,
@@ -247,6 +248,7 @@ public Package.Builder newPackageBuilder(
         associatedModuleVersion,
         starlarkSemantics.getBool(BuildLanguageOptions.INCOMPATIBLE_NO_IMPLICIT_FILE_EXPORT),
         repositoryMapping,
+        mainRepositoryMapping,
         cpuBoundSemaphore,
         packageOverheadEstimator,
         generatorMap,
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
index 9414b20e96511c..3c59e5727fd5ee 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
@@ -17,6 +17,7 @@
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.Attribute.StarlarkComputedDefaultTemplate.CannotPrecomputeDefaultsException;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/StarlarkCallbackHelper.java b/src/main/java/com/google/devtools/build/lib/packages/StarlarkCallbackHelper.java
index 35795f2ddb5b67..5290a5aa088718 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/StarlarkCallbackHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/StarlarkCallbackHelper.java
@@ -15,6 +15,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import net.starlark.java.eval.EvalException;
@@ -69,7 +70,8 @@ public Object call(EventHandler eventHandler, Structure struct, Object... argume
       // But I don't think implicit outputs or computed defaults care about identity.
       StarlarkThread thread = StarlarkThread.createTransient(mu, starlarkSemantics);
       thread.setPrintHandler(Event.makeDebugPrintHandler(eventHandler));
-      new BazelStarlarkContext(BazelStarlarkContext.Phase.LOADING).storeInThread(thread);
+      new BazelStarlarkContext(BazelStarlarkContext.Phase.LOADING, /* mainRepoMapping= */ null)
+          .storeInThread(thread);
       return Starlark.call(
           thread, callback, buildArgumentList(struct, arguments), /*kwargs=*/ ImmutableMap.of());
     } catch (ClassCastException | IllegalArgumentException e) { // TODO(adonovan): investigate
diff --git a/src/main/java/com/google/devtools/build/lib/packages/StarlarkNativeModule.java b/src/main/java/com/google/devtools/build/lib/packages/StarlarkNativeModule.java
index d7cc82d36ebc0f..94b77d9675000c 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/StarlarkNativeModule.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/StarlarkNativeModule.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.Iterators;
 import com.google.common.collect.UnmodifiableIterator;
 import com.google.common.flogger.GoogleLogger;
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/TargetDefinitionContext.java b/src/main/java/com/google/devtools/build/lib/packages/TargetDefinitionContext.java
index 86283dd8f610bc..8a8a41e0c63044 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/TargetDefinitionContext.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/TargetDefinitionContext.java
@@ -14,6 +14,9 @@
 
 package com.google.devtools.build.lib.packages;
 
+import com.google.devtools.build.lib.cmdline.BazelStarlarkContext;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
+
 /**
  * A context object, usually stored in a {@link StarlarkThread}, upon which rules and symbolic
  * macros can be instantiated.
@@ -40,7 +43,7 @@ public NameConflictException(String message) {
     }
   }
 
-  protected TargetDefinitionContext(Phase phase) {
-    super(phase);
+  protected TargetDefinitionContext(Phase phase, RepositoryMapping mainRepoMapping) {
+    super(phase, () -> mainRepoMapping);
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
index 8df4373ef30585..3b6311df3849a5 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
@@ -845,7 +845,6 @@ private BzlLoadValue computeInternalWithCompiledBzl(
         BazelModuleContext.create(
             label,
             repoMapping,
-            mainRepoMapping,
             prog.getFilename(),
             ImmutableList.copyOf(loadMap.values()),
             transitiveDigest);
@@ -864,7 +863,8 @@ private BzlLoadValue computeInternalWithCompiledBzl(
             transitiveDigest,
             ruleClassProvider.getToolsRepository(),
             ruleClassProvider.getNetworkAllowlistForTests(),
-            ruleClassProvider.getConfigurationFragmentMap());
+            ruleClassProvider.getConfigurationFragmentMap(),
+            mainRepoMapping);
 
     // executeBzlFile may post events to the Environment's handler, but events do not matter when
     // caching BzlLoadValues. Note that executing the code mutates the Module and
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
index d1152c57e67a9a..846c7da8b341bb 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
@@ -30,6 +30,7 @@
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.RepositoryMapping;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.io.FileSymlinkException;
 import com.google.devtools.build.lib.io.InconsistentFilesystemException;
@@ -926,6 +927,9 @@ private LoadedPackage loadPackage(
     RepositoryMappingValue repositoryMappingValue =
         (RepositoryMappingValue)
             env.getValue(RepositoryMappingValue.key(packageId.getRepository()));
+    RepositoryMappingValue mainRepositoryMappingValue =
+            (RepositoryMappingValue)
+                    env.getValue(RepositoryMappingValue.key(RepositoryName.MAIN));
     RootedPath buildFileRootedPath = packageLookupValue.getRootedPath(packageId);
     FileValue buildFileValue = getBuildFileValue(env, buildFileRootedPath);
     RuleVisibility defaultVisibility = PrecomputedValue.DEFAULT_VISIBILITY.get(env);
@@ -961,6 +965,7 @@ private LoadedPackage loadPackage(
     }
     String workspaceName = workspaceNameValue.getName();
     RepositoryMapping repositoryMapping = repositoryMappingValue.getRepositoryMapping();
+    RepositoryMapping mainRepositoryMapping = mainRepositoryMappingValue.getRepositoryMapping();
     ImmutableSet<PathFragment> repositoryIgnoredPatterns =
         repositoryIgnoredPackagePrefixes.getPatterns();
     Label preludeLabel = null;
@@ -1108,6 +1113,7 @@ private LoadedPackage loadPackage(
               repositoryMappingValue.getAssociatedModuleVersion(),
               starlarkBuiltinsValue.starlarkSemantics,
               repositoryMapping,
+              mainRepositoryMapping,
               cpuBoundSemaphore.get(),
               /* (Nullable) */ compiled.generatorMap,
               configSettingVisibilityPolicy,
diff --git a/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java b/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
index 99c70114afc71c..15ff14182f8db2 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
@@ -168,7 +168,7 @@ private Package.Builder pkgBuilder(String name) {
         Optional.empty(),
         /* noImplicitFileExport= */ true,
         /* repositoryMapping= */ RepositoryMapping.ALWAYS_FALLBACK,
-        /* cpuBoundSemaphore= */ null,
+        /* cpuBoundSemaphore= */ mainRepositoryMapping, null,
         PackageOverheadEstimator.NOOP_ESTIMATOR,
         /* generatorMap= */ null,
         /* configSettingVisibilityPolicy= */ null,
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
index ced3bf236d95a8..19b263fa7c1459 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
@@ -271,7 +271,7 @@ private Package.Builder createDummyPackageBuilder() {
         Optional.empty(),
         StarlarkSemantics.DEFAULT,
         /* repositoryMapping= */ RepositoryMapping.ALWAYS_FALLBACK,
-        /* cpuBoundSemaphore= */ null,
+        /* cpuBoundSemaphore= */ mainRepositoryMapping, null,
         /* generatorMap= */ null,
         /* configSettingVisibilityPolicy= */ null,
         /* globber= */ null);
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
index 23e4705bc72669..c47adcd4e7bffb 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
@@ -63,7 +63,7 @@ private Package.Builder newBuilder(PackageIdentifier id, Path filename) {
             Optional.empty(),
             StarlarkSemantics.DEFAULT,
             /* repositoryMapping= */ RepositoryMapping.ALWAYS_FALLBACK,
-            /* cpuBoundSemaphore= */ null,
+            /* cpuBoundSemaphore= */ mainRepositoryMapping, null,
             /* generatorMap= */ null,
             /* configSettingVisibilityPolicy= */ null,
             /* globber= */ null)
diff --git a/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java b/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
index 03cfff25331a69..eb3c32123d28c1 100644
--- a/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
@@ -163,7 +163,8 @@ private void newThread(StarlarkThread thread) {
             /* transitiveDigest= */ new byte[0], // dummy value for tests
             TestConstants.TOOLS_REPOSITORY,
             /* networkAllowlistForTests= */ Optional.empty(),
-            fragmentNameToClass)
+            fragmentNameToClass,
+            /* mainRepoMapping= */ null)
         .storeInThread(thread);
   }
 
@@ -187,7 +188,6 @@ private Object newModule(ImmutableMap.Builder<String, Object> predeclared) {
     return BazelModuleContext.create(
         label,
         RepositoryMapping.ALWAYS_FALLBACK,
-        /* mainRepoMapping= */ null,
         "test/label.bzl",
         /* loads= */ ImmutableList.of(),
         /* bzlTransitiveDigest= */ new byte[0]);