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 7dd00513ca5471..0eae9954100559 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
@@ -256,7 +256,16 @@ public ImmutableMap<RepositoryName, RepositoryName> getRepositoryMapping(
       throw new UnsupportedOperationException("Can only access the external package repository"
           + "mappings from the //external package");
     }
-    return externalPackageRepositoryMappings.getOrDefault(repository, ImmutableMap.of());
+
+    // We are passed a repository name as seen from the main repository, not necessarily
+    // a canonical repository name. So, we first have to find the canonical name for the
+    // repository in question before we can look up the mapping for it.
+    RepositoryName actualRepositoryName =
+        externalPackageRepositoryMappings
+            .getOrDefault(RepositoryName.MAIN, ImmutableMap.of())
+            .getOrDefault(repository, repository);
+
+    return externalPackageRepositoryMappings.getOrDefault(actualRepositoryName, ImmutableMap.of());
   }
 
   /** Get the repository mapping for this package. */
diff --git a/src/test/shell/bazel/workspace_test.sh b/src/test/shell/bazel/workspace_test.sh
index 0ff8d6615aaf62..704e19593258e0 100755
--- a/src/test/shell/bazel/workspace_test.sh
+++ b/src/test/shell/bazel/workspace_test.sh
@@ -934,5 +934,65 @@ EOF
 
 }
 
+test_remap_toolchains_from_qualified_load() {
+    cat > WORKSPACE <<'EOF'
+workspace(name = "my_ws")
+
+register_toolchains("@my_ws//toolchains:sample_toolchain")
+EOF
+    mkdir toolchains
+    cat > toolchains/toolchain.bzl <<'EOF'
+def _impl(ctx):
+  return [platform_common.ToolchainInfo()]
+
+mytoolchain = rule(
+  implementation = _impl,
+  attrs = {},
+)
+EOF
+    cat > toolchains/rule.bzl <<'EOF'
+def _impl(ctx):
+  # Ensure the toolchain is available under the requested (non-canonical)
+  # name
+  print("toolchain is %s" %
+        (ctx.toolchains["@my_ws//toolchains:my_toolchain_type"],))
+  pass
+
+testrule = rule(
+  implementation = _impl,
+  attrs = {},
+  toolchains = ["@my_ws//toolchains:my_toolchain_type"],
+)
+EOF
+    cat > toolchains/BUILD <<'EOF'
+load("@my_ws//toolchains:toolchain.bzl", "mytoolchain")
+load("@my_ws//toolchains:rule.bzl", "testrule")
+
+toolchain_type(name = "my_toolchain_type")
+mytoolchain(name = "thetoolchain")
+
+toolchain(
+  name = "sample_toolchain",
+  toolchain = "@my_ws//toolchains:thetoolchain",
+  toolchain_type = "@my_ws//toolchains:my_toolchain_type",
+)
+
+testrule(
+  name = "emptytoolchainconsumer",
+)
+EOF
+
+    bazel build --incompatible_remap_main_repo=true @my_ws//toolchains/... \
+          || fail "expected success"
+
+    # Additionally check, that nothing goes wrong flipping the remapping
+    # off and on again.
+    bazel build --incompatible_remap_main_repo=false @my_ws//toolchains/... \
+          || fail "expected success"
+
+    bazel build --incompatible_remap_main_repo=true @my_ws//toolchains/... \
+          || fail "expected success"
+}
+
 
 run_suite "workspace tests"