diff --git a/clang/include/clang/Frontend/MultiplexConsumer.h b/clang/include/clang/Frontend/MultiplexConsumer.h
index ca6ed8310ae9e3..3054e1842811d4 100644
--- a/clang/include/clang/Frontend/MultiplexConsumer.h
+++ b/clang/include/clang/Frontend/MultiplexConsumer.h
@@ -65,6 +65,7 @@ class MultiplexConsumer : public SemaConsumer {
   void HandleTopLevelDeclInObjCContainer(DeclGroupRef D) override;
   void HandleImplicitImportDecl(ImportDecl *D) override;
   void CompleteTentativeDefinition(VarDecl *D) override;
+  void CompleteExternalDeclaration(VarDecl *D) override;
   void AssignInheritanceModel(CXXRecordDecl *RD) override;
   void HandleVTable(CXXRecordDecl *RD) override;
   ASTMutationListener *GetASTMutationListener() override;
diff --git a/clang/lib/Frontend/MultiplexConsumer.cpp b/clang/lib/Frontend/MultiplexConsumer.cpp
index 04e896296c95c2..5abbb3a235b49f 100644
--- a/clang/lib/Frontend/MultiplexConsumer.cpp
+++ b/clang/lib/Frontend/MultiplexConsumer.cpp
@@ -322,6 +322,11 @@ void MultiplexConsumer::CompleteTentativeDefinition(VarDecl *D) {
     Consumer->CompleteTentativeDefinition(D);
 }
 
+void MultiplexConsumer::CompleteExternalDeclaration(VarDecl *D) {
+  for (auto &Consumer : Consumers)
+    Consumer->CompleteExternalDeclaration(D);
+}
+
 void MultiplexConsumer::AssignInheritanceModel(CXXRecordDecl *RD) {
   for (auto &Consumer : Consumers)
     Consumer->AssignInheritanceModel(RD);