diff --git a/include/llvm/ADT/StringSwitch.h b/include/llvm/ADT/StringSwitch.h
index 42b0fc4bc44..dc3b15b8111 100644
--- a/include/llvm/ADT/StringSwitch.h
+++ b/include/llvm/ADT/StringSwitch.h
@@ -53,6 +53,13 @@ public:
   explicit StringSwitch(StringRef S)
   : Str(S), Result(nullptr) { }
 
+  // StringSwitch is neither copyable nor movable.
+  StringSwitch(const StringSwitch &) = delete;
+  StringSwitch(StringSwitch &&) = delete;
+  void operator=(const StringSwitch &) = delete;
+  void operator=(StringSwitch &&) = delete;
+  ~StringSwitch() = default;
+
   template<unsigned N>
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Case(const char (&S)[N], const T& Value) {
diff --git a/lib/Passes/PassBuilder.cpp b/lib/Passes/PassBuilder.cpp
index 6c0ceb0a3d6..594fe814c83 100644
--- a/lib/Passes/PassBuilder.cpp
+++ b/lib/Passes/PassBuilder.cpp
@@ -334,13 +334,13 @@ bool PassBuilder::parseModulePassName(ModulePassManager &MPM, StringRef Name,
       return false;
     assert(Matches.size() == 3 && "Must capture two matched strings!");
 
-    auto L = StringSwitch<OptimizationLevel>(Matches[2])
-                 .Case("O0", O0)
-                 .Case("O1", O1)
-                 .Case("O2", O2)
-                 .Case("O3", O3)
-                 .Case("Os", Os)
-                 .Case("Oz", Oz);
+    OptimizationLevel L = StringSwitch<OptimizationLevel>(Matches[2])
+        .Case("O0", O0)
+        .Case("O1", O1)
+        .Case("O2", O2)
+        .Case("O3", O3)
+        .Case("Os", Os)
+        .Case("Oz", Oz);
 
     if (Matches[1] == "default") {
       addPerModuleDefaultPipeline(MPM, L, DebugLogging);