diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 796b532..6bb2034 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -930,6 +930,13 @@
 static Decl::Kind getKind(const Decl *D) { return D->getKind(); }
 static Decl::Kind getKind(const DeclContext *DC) { return DC->getDeclKind(); }
 
+int64_t Decl::getID() const {
+  Optional<int64_t> Out = getASTContext().getAllocator().identifyObject(this);
+  assert(Out && "Wrong allocator used");
+  assert(*Out % alignof(Decl) == 0 && "Wrong alignment information");
+  return *Out / alignof(Decl);
+}
+
 const FunctionType *Decl::getFunctionType(bool BlocksToo) const {
   QualType Ty;
   if (const auto *D = dyn_cast<ValueDecl>(this))