Index: unittests/ADT/CMakeLists.txt
===================================================================
--- unittests/ADT/CMakeLists.txt
+++ unittests/ADT/CMakeLists.txt
@@ -56,6 +56,7 @@
   StringExtrasTest.cpp
   StringMapTest.cpp
   StringRefTest.cpp
+  StringSwitchTest.cpp
   TinyPtrVectorTest.cpp
   TripleTest.cpp
   TwineTest.cpp
Index: unittests/ADT/StringSwitchTest.cpp
===================================================================
--- /dev/null
+++ unittests/ADT/StringSwitchTest.cpp
@@ -0,0 +1,104 @@
+//===- llvm/unittest/ADT/StringSwitchTest.cpp - StringSwitch unit tests ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringSwitch.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+TEST(StringSwitchTest, Case) {
+  auto Translate = [](StringRef S) {
+    return llvm::StringSwitch<int>(S)
+        .Case("0", 0)
+        .Case("1", 1)
+        .Case("2", 2)
+        .Case("3", 3)
+        .Case("4", 4)
+        .Case("5", 5)
+        .Case("6", 6)
+        .Case("7", 7)
+        .Case("8", 8)
+        .Case("9", 9)
+        .Case("A", 10)
+        .Case("B", 11)
+        .Case("C", 12)
+        .Case("D", 13)
+        .Case("E", 14)
+        .Case("F", 15)
+        .Default(-1);
+  };
+  EXPECT_EQ(1, Translate("1"));
+  EXPECT_EQ(2, Translate("2"));
+  EXPECT_EQ(11, Translate("B"));
+  EXPECT_EQ(-1, Translate("b"));
+  EXPECT_EQ(-1, Translate(""));
+  EXPECT_EQ(-1, Translate("Test"));
+}
+
+TEST(StringSwitchTest, StartsWith) {
+  auto Translate = [](StringRef S) {
+    return llvm::StringSwitch<std::function<int(int, int)>>(S)
+        .StartsWith("add", [](int X, int Y) { return X + Y; })
+        .StartsWith("sub", [](int X, int Y) { return X - Y; })
+        .StartsWith("mul", [](int X, int Y) { return X * Y; })
+        .StartsWith("div", [](int X, int Y) { return X / Y; })
+        .Default([](int X, int Y) { return 0; });
+  };
+
+  EXPECT_EQ(15, Translate("adder")(10, 5));
+  EXPECT_EQ(5, Translate("subtracter")(10, 5));
+  EXPECT_EQ(50, Translate("multiplier")(10, 5));
+  EXPECT_EQ(2, Translate("divider")(10, 5));
+
+  EXPECT_EQ(0, Translate("nothing")(10, 5));
+  EXPECT_EQ(0, Translate("ADDER")(10, 5));
+}
+
+TEST(StringSwitchTest, EndsWith) {
+  enum class Suffix { Possible, PastTense, Process, InProgressAction, Unknown };
+
+  auto Translate = [](StringRef S) {
+    return llvm::StringSwitch<Suffix>(S)
+        .EndsWith("able", Suffix::Possible)
+        .EndsWith("ed", Suffix::PastTense)
+        .EndsWith("ation", Suffix::Process)
+        .EndsWith("ing", Suffix::InProgressAction)
+        .Default(Suffix::Unknown);
+  };
+
+  EXPECT_EQ(Suffix::Possible, Translate("optimizable"));
+  EXPECT_EQ(Suffix::PastTense, Translate("optimized"));
+  EXPECT_EQ(Suffix::Process, Translate("optimization"));
+  EXPECT_EQ(Suffix::InProgressAction, Translate("optimizing"));
+  EXPECT_EQ(Suffix::Unknown, Translate("optimizer"));
+  EXPECT_EQ(Suffix::Unknown, Translate("OPTIMIZABLE"));
+}
+
+TEST(StringSwitchTest, Cases) {
+  enum class OSType { Windows, Linux, Unknown };
+
+  auto Translate = [](StringRef S) {
+    return llvm::StringSwitch<OSType>(S)
+        .Cases("windows", "win32", "winnt", OSType::Windows)
+        .Cases("linux", "unix", "*nix", "posix", OSType::Linux)
+        .Default(OSType::Unknown);
+  };
+
+  EXPECT_EQ(OSType::Windows, Translate("windows"));
+  EXPECT_EQ(OSType::Windows, Translate("win32"));
+  EXPECT_EQ(OSType::Windows, Translate("winnt"));
+
+  EXPECT_EQ(OSType::Linux, Translate("linux"));
+  EXPECT_EQ(OSType::Linux, Translate("unix"));
+  EXPECT_EQ(OSType::Linux, Translate("*nix"));
+  EXPECT_EQ(OSType::Linux, Translate("posix"));
+
+  EXPECT_EQ(OSType::Unknown, Translate("Windows"));
+  EXPECT_EQ(OSType::Unknown, Translate(""));
+}