diff --git a/llvm/include/llvm/ADT/StringExtras.h b/llvm/include/llvm/ADT/StringExtras.h
--- a/llvm/include/llvm/ADT/StringExtras.h
+++ b/llvm/include/llvm/ADT/StringExtras.h
@@ -451,14 +451,8 @@
   return Str.size();
 }
 
-inline size_t join_items_size() { return 0; }
-
-template <typename A1> inline size_t join_items_size(const A1 &A) {
-  return join_one_item_size(A);
-}
-template <typename A1, typename... Args>
-inline size_t join_items_size(const A1 &A, Args &&... Items) {
-  return join_one_item_size(A) + join_items_size(std::forward<Args>(Items)...);
+template <typename... Args> inline size_t join_items_size(Args &&...Items) {
+  return (0 + ... + join_one_item_size(std::forward<Args>(Items)));
 }
 
 } // end namespace detail