diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index f68de26cde3b..835609585ebb 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -6173,6 +6173,8 @@ TreeTransform<Derived>::TransformCharacterLiteral(CharacterLiteral *E) {
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUserDefinedLiteral(UserDefinedLiteral *E) {
+  if (FunctionDecl *FD = E->getDirectCallee())
+    SemaRef.MarkFunctionReferenced(E->getLocStart(), FD);
   return SemaRef.MaybeBindToTemporary(E);
 }
 
diff --git a/clang/test/SemaCXX/cxx11-user-defined-literals-unused.cpp b/clang/test/SemaCXX/cxx11-user-defined-literals-unused.cpp
new file mode 100644
index 000000000000..cd93ffbf21ed
--- /dev/null
+++ b/clang/test/SemaCXX/cxx11-user-defined-literals-unused.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wunused
+
+namespace {
+double operator"" _x(long double value) { return double(value); }
+int operator"" _ii(long double value) { return int(value); } // expected-warning {{not needed and will not be emitted}}
+}
+
+namespace rdar13589856 {
+  template<class T> double value() { return 3.2_x; }
+  template<class T> int valuei() { return 3.2_ii; }
+
+  double get_value() { return value<double>(); }
+}