diff --git a/include/llvm/ADT/STLExtras.h b/include/llvm/ADT/STLExtras.h
index eb515fd4583..e6215e4ae5b 100644
--- a/include/llvm/ADT/STLExtras.h
+++ b/include/llvm/ADT/STLExtras.h
@@ -382,6 +382,11 @@ struct build_index_impl<0, I...> : index_sequence<I...> {};
 template <class... Ts>
 struct index_sequence_for : build_index_impl<sizeof...(Ts)> {};
 
+/// Utility type to build an inheritance chain that makes it easy to rank
+/// overload candidates.
+template <int N> struct rank : rank<N - 1> {};
+template <> struct rank<0> {};
+
 //===----------------------------------------------------------------------===//
 //     Extra additions for arrays
 //===----------------------------------------------------------------------===//
diff --git a/unittests/ADT/CMakeLists.txt b/unittests/ADT/CMakeLists.txt
index 83d6eb53d83..72d0c00a450 100644
--- a/unittests/ADT/CMakeLists.txt
+++ b/unittests/ADT/CMakeLists.txt
@@ -34,6 +34,7 @@ set(ADTSources
   PriorityWorklistTest.cpp
   RangeAdapterTest.cpp
   SCCIteratorTest.cpp
+  STLExtrasTest.cpp
   ScopeExitTest.cpp
   SequenceTest.cpp
   SetVectorTest.cpp
diff --git a/unittests/ADT/STLExtrasTest.cpp b/unittests/ADT/STLExtrasTest.cpp
new file mode 100644
index 00000000000..dc62b03741c
--- /dev/null
+++ b/unittests/ADT/STLExtrasTest.cpp
@@ -0,0 +1,40 @@
+//===- STLExtrasTest.cpp - Unit tests for STL 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/STLExtras.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+int f(rank<0>) { return 0; }
+int f(rank<1>) { return 1; }
+int f(rank<2>) { return 2; }
+int f(rank<4>) { return 4; }
+
+TEST(STLExtrasTest, Rank) {
+  // We shouldn't get ambiguities and should select the overload of the same
+  // rank as the argument.
+  EXPECT_EQ(0, f(rank<0>()));
+  EXPECT_EQ(1, f(rank<1>()));
+  EXPECT_EQ(2, f(rank<2>()));
+
+  // This overload is missing so we end up back at 2.
+  EXPECT_EQ(2, f(rank<3>()));
+
+  // But going past 3 should work fine.
+  EXPECT_EQ(4, f(rank<4>()));
+
+  // And we can even go higher and just fall back to the last overload.
+  EXPECT_EQ(4, f(rank<5>()));
+  EXPECT_EQ(4, f(rank<6>()));
+}
+
+}