Index: include/llvm/ADT/StringSwitch.h
===================================================================
--- include/llvm/ADT/StringSwitch.h
+++ include/llvm/ADT/StringSwitch.h
@@ -46,12 +46,12 @@
 
   /// \brief The pointer to the result of this switch statement, once known,
   /// null before that.
-  const T *Result;
+  Optional<T> Result;
 
 public:
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   explicit StringSwitch(StringRef S)
-  : Str(S), Result(nullptr) { }
+  : Str(S), Result() { }
 
   // StringSwitch is not copyable.
   StringSwitch(const StringSwitch &) = delete;
@@ -61,187 +61,154 @@
     *this = std::move(other);
   }
   StringSwitch &operator=(StringSwitch &&other) {
-    Str = other.Str;
-    Result = other.Result;
+    Str = std::move(other.Str);
+    Result = std::move(other.Result);
     return *this;
   }
 
   ~StringSwitch() = default;
 
   // Case-sensitive case matchers
-  template<unsigned N>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch& Case(const char (&S)[N], const T& Value) {
-    assert(N);
-    if (!Result && N-1 == Str.size() &&
-        (N == 1 || std::memcmp(S, Str.data(), N-1) == 0)) {
-      Result = &Value;
+  StringSwitch &Case(StringLiteral S, T Value) {
+    if (!Result && Str == S) {
+      Result = std::move(Value);
     }
     return *this;
   }
 
   template<unsigned N>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch& EndsWith(const char (&S)[N], const T &Value) {
+  StringSwitch& EndsWith(const char (&S)[N], T Value) {
     assert(N);
     if (!Result && Str.size() >= N-1 &&
         (N == 1 || std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0)) {
-      Result = &Value;
+      Result = std::move(Value);
     }
     return *this;
   }
 
   template<unsigned N>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch& StartsWith(const char (&S)[N], const T &Value) {
+  StringSwitch& StartsWith(const char (&S)[N], T Value) {
     assert(N);
     if (!Result && Str.size() >= N-1 &&
         (N == 1 || std::memcmp(S, Str.data(), N-1) == 0)) {
-      Result = &Value;
+      Result = std::move(Value);
     }
     return *this;
   }
 
-  template<unsigned N0, unsigned N1>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const T& Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, T Value) {
     return Case(S0, Value).Case(S1, Value);
   }
 
-  template<unsigned N0, unsigned N1, unsigned N2>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const T& Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      T Value) {
     return Case(S0, Value).Cases(S1, S2, Value);
   }
 
-  template<unsigned N0, unsigned N1, unsigned N2, unsigned N3>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const T& Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, Value);
   }
 
-  template<unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const T& Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4,
-            unsigned N5>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const char (&S5)[N5],
-                      const T &Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, StringLiteral S5,
+                      T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, S5, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4,
-            unsigned N5, unsigned N6>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const char (&S5)[N5],
-                      const char (&S6)[N6], const T &Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, StringLiteral S5,
+                      StringLiteral S6, T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4,
-            unsigned N5, unsigned N6, unsigned N7>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const char (&S5)[N5],
-                      const char (&S6)[N6], const char (&S7)[N7],
-                      const T &Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, StringLiteral S5,
+                      StringLiteral S6, StringLiteral S7, T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4,
-            unsigned N5, unsigned N6, unsigned N7, unsigned N8>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const char (&S5)[N5],
-                      const char (&S6)[N6], const char (&S7)[N7],
-                      const char (&S8)[N8], const T &Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, StringLiteral S5,
+                      StringLiteral S6, StringLiteral S7, StringLiteral S8,
+                      T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, S8, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4,
-            unsigned N5, unsigned N6, unsigned N7, unsigned N8, unsigned N9>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  StringSwitch &Cases(const char (&S0)[N0], const char (&S1)[N1],
-                      const char (&S2)[N2], const char (&S3)[N3],
-                      const char (&S4)[N4], const char (&S5)[N5],
-                      const char (&S6)[N6], const char (&S7)[N7],
-                      const char (&S8)[N8], const char (&S9)[N9],
-                      const T &Value) {
+  StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                      StringLiteral S3, StringLiteral S4, StringLiteral S5,
+                      StringLiteral S6, StringLiteral S7, StringLiteral S8,
+                      StringLiteral S9, T Value) {
     return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, S8, S9, Value);
   }
 
   // Case-insensitive case matchers.
-  template <unsigned N>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &CaseLower(const char (&S)[N],
-                                                       const T &Value) {
-    if (!Result && Str.equals_lower(StringRef(S, N - 1)))
-      Result = &Value;
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &CaseLower(StringLiteral S, T Value) {
+    if (!Result && Str.equals_lower(S))
+      Result = std::move(Value);
 
     return *this;
   }
 
-  template <unsigned N>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &EndsWithLower(const char (&S)[N],
-                                                           const T &Value) {
-    if (!Result && Str.endswith_lower(StringRef(S, N - 1)))
-      Result = &Value;
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &EndsWithLower(StringLiteral S, T Value) {
+    if (!Result && Str.endswith_lower(S))
+      Result = Value;
 
     return *this;
   }
 
-  template <unsigned N>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &StartsWithLower(const char (&S)[N],
-                                                             const T &Value) {
-    if (!Result && Str.startswith_lower(StringRef(S, N - 1)))
-      Result = &Value;
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &StartsWithLower(StringLiteral S, T Value) {
+    if (!Result && Str.startswith_lower(S))
+      Result = std::move(Value);
 
     return *this;
   }
-  template <unsigned N0, unsigned N1>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &
-  CasesLower(const char (&S0)[N0], const char (&S1)[N1], const T &Value) {
+
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, T Value) {
     return CaseLower(S0, Value).CaseLower(S1, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &
-  CasesLower(const char (&S0)[N0], const char (&S1)[N1], const char (&S2)[N2],
-             const T &Value) {
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                           T Value) {
     return CaseLower(S0, Value).CasesLower(S1, S2, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &
-  CasesLower(const char (&S0)[N0], const char (&S1)[N1], const char (&S2)[N2],
-             const char (&S3)[N3], const T &Value) {
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                           StringLiteral S3, T Value) {
     return CaseLower(S0, Value).CasesLower(S1, S2, S3, Value);
   }
 
-  template <unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE StringSwitch &
-  CasesLower(const char (&S0)[N0], const char (&S1)[N1], const char (&S2)[N2],
-             const char (&S3)[N3], const char (&S4)[N4], const T &Value) {
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
+                           StringLiteral S3, StringLiteral S4, T Value) {
     return CaseLower(S0, Value).CasesLower(S1, S2, S3, S4, Value);
   }
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
-  R Default(const T &Value) const {
+  R Default(T Value) const {
     if (Result)
       return *Result;
     return Value;
Index: unittests/ADT/StringSwitchTest.cpp
===================================================================
--- unittests/ADT/StringSwitchTest.cpp
+++ unittests/ADT/StringSwitchTest.cpp
@@ -158,7 +158,7 @@
 
   auto Translate = [](StringRef S) {
     return llvm::StringSwitch<OSType>(S)
-        .Cases("wind\0ws", "win32", "winnt", OSType::Windows)
+        .Cases(llvm::StringRef("wind\0ws",7), "win32", "winnt", OSType::Windows)
         .Cases("linux", "unix", "*nix", "posix", OSType::Linux)
         .Default(OSType::Unknown);
   };
@@ -184,7 +184,8 @@
 
   auto Translate = [](StringRef S) {
     return llvm::StringSwitch<OSType>(S)
-        .CasesLower("wind\0ws", "win32", "winnt", OSType::Windows)
+        .CasesLower(llvm::StringRef("wind\0ws", 7), "win32", "winnt",
+                    OSType::Windows)
         .CasesLower("linux", "unix", "*nix", "posix", OSType::Linux)
         .Default(OSType::Unknown);
   };