Index: include/llvm/ADT/StringExtras.h
===================================================================
--- include/llvm/ADT/StringExtras.h
+++ include/llvm/ADT/StringExtras.h
@@ -155,6 +155,8 @@
 /// it if it is not printable or if it is an escape char.
 void PrintEscapedString(StringRef Name, raw_ostream &Out);
 
+namespace detail {
+
 template <typename IteratorT>
 inline std::string join_impl(IteratorT Begin, IteratorT End,
                              StringRef Separator, std::input_iterator_tag) {
@@ -189,12 +191,61 @@
   return S;
 }
 
+template <typename Sep>
+inline void join_items_impl(std::string &Result, Sep Separator) {}
+
+template <typename Sep, typename Arg>
+inline void join_items_impl(std::string &Result, Sep Separator,
+                            const Arg &Item) {
+  Result += Item;
+}
+
+template <typename Sep, typename Arg1, typename Arg2, typename... Args>
+inline void join_items_impl(std::string &Result, Sep Separator, const Arg1 &A1,
+                            const Arg2 &A2, Args &&... Items) {
+  Result += A1;
+  Result += Separator;
+  join_items_impl(Result, Separator, A2, std::forward<Args>(Items)...);
+}
+
+inline size_t join_one_item_size(char C) { return 1; }
+inline size_t join_one_item_size(const char *S) { return S ? ::strlen(S) : 0; }
+
+template <typename T> inline size_t join_one_item_size(const T &Str) {
+  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 A2, typename... Args>
+inline size_t join_items_size(const A1 &A, const A2 &B, Args &&... Items) {
+  return join_one_item_size(A) +
+         join_items_size(B, std::forward<Args>(Items)...);
+}
+}
+
 /// Joins the strings in the range [Begin, End), adding Separator between
 /// the elements.
 template <typename IteratorT>
 inline std::string join(IteratorT Begin, IteratorT End, StringRef Separator) {
   typedef typename std::iterator_traits<IteratorT>::iterator_category tag;
-  return join_impl(Begin, End, Separator, tag());
+  return detail::join_impl(Begin, End, Separator, tag());
+}
+
+template <typename Sep, typename... Args>
+inline std::string join_items(Sep Separator, Args &&... Items) {
+  std::string Result;
+  if (sizeof...(Items) == 0)
+    return Result;
+
+  size_t NS = detail::join_one_item_size(Separator);
+  size_t NI = detail::join_items_size(std::forward<Args>(Items)...);
+  Result.reserve(NI + (sizeof...(Items) - 1) * NS);
+  detail::join_items_impl(Result, Separator, std::forward<Args>(Items)...);
+  return Result;
 }
 
 } // End llvm namespace
Index: unittests/ADT/CMakeLists.txt
===================================================================
--- unittests/ADT/CMakeLists.txt
+++ unittests/ADT/CMakeLists.txt
@@ -53,6 +53,7 @@
   SparseBitVectorTest.cpp
   SparseMultiSetTest.cpp
   SparseSetTest.cpp
+  StringExtrasTest.cpp
   StringMapTest.cpp
   StringRefTest.cpp
   TinyPtrVectorTest.cpp
Index: unittests/ADT/StringExtrasTest.cpp
===================================================================
--- /dev/null
+++ unittests/ADT/StringExtrasTest.cpp
@@ -0,0 +1,52 @@
+//===- StringExtrasTest.cpp - Unit tests for String extras ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringExtras.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+TEST(StringExtrasTest, Join) {
+  std::vector<std::string> Items;
+  EXPECT_EQ("", join(Items.begin(), Items.end(), " <sep> "));
+
+  Items = {"foo"};
+  EXPECT_EQ("foo", join(Items.begin(), Items.end(), " <sep> "));
+
+  Items = {"foo", "bar"};
+  EXPECT_EQ("foo <sep> bar", join(Items.begin(), Items.end(), " <sep> "));
+
+  Items = {"foo", "bar", "baz"};
+  EXPECT_EQ("foo <sep> bar <sep> baz",
+            join(Items.begin(), Items.end(), " <sep> "));
+}
+
+TEST(StringExtrasTest, JoinItems) {
+  const char *Foo = "foo";
+  std::string Bar = "bar";
+  llvm::StringRef Baz = "baz";
+  char X = 'x';
+
+  EXPECT_EQ("", join_items(" <sep> "));
+  EXPECT_EQ("", join_items('/'));
+
+  EXPECT_EQ("foo", join_items(" <sep> ", Foo));
+  EXPECT_EQ("foo", join_items('/', Foo));
+
+  EXPECT_EQ("foo <sep> bar", join_items(" <sep> ", Foo, Bar));
+  EXPECT_EQ("foo/bar", join_items('/', Foo, Bar));
+
+  EXPECT_EQ("foo <sep> bar <sep> baz", join_items(" <sep> ", Foo, Bar, Baz));
+  EXPECT_EQ("foo/bar/baz", join_items('/', Foo, Bar, Baz));
+
+  EXPECT_EQ("foo <sep> bar <sep> baz <sep> x",
+            join_items(" <sep> ", Foo, Bar, Baz, X));
+
+  EXPECT_EQ("foo/bar/baz/x", join_items('/', Foo, Bar, Baz, X));
+}