diff --git a/llvm/include/llvm/ADT/TypeSwitch.h b/llvm/include/llvm/ADT/TypeSwitch.h
--- a/llvm/include/llvm/ADT/TypeSwitch.h
+++ b/llvm/include/llvm/ADT/TypeSwitch.h
@@ -35,7 +35,12 @@
   /// Invoke a case on the derived class with multiple case types.
   template <typename CaseT, typename CaseT2, typename... CaseTs,
             typename CallableT>
-  DerivedT &Case(CallableT &&caseFn) {
+  // This is marked always_inline and nodebug so it doesn't show up in stack
+  // traces at -O0 (or other optimization levels).  Large TypeSwitch's are
+  // common, are equivalent to a switch, and don't add any value to stack
+  // traces.
+  LLVM_ATTRIBUTE_ALWAYS_INLINE LLVM_ATTRIBUTE_NODEBUG DerivedT &
+  Case(CallableT &&caseFn) {
     DerivedT &derived = static_cast<DerivedT &>(*this);
     return derived.template Case<CaseT>(caseFn)
         .template Case<CaseT2, CaseTs...>(caseFn);
diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -248,6 +248,15 @@
 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline
 #endif
 
+/// LLVM_ATTRIBUTE_NO_DEBUG - On compilers where we have a directive to do
+/// so, mark a method "no debug" because debug info makes the debugger
+/// experience worse.  GCC introduced this in GCC 4.0
+#if __has_attribute(nodebug) || LLVM_GNUC_PREREQ(4, 0, 0)
+#define LLVM_ATTRIBUTE_NODEBUG __attribute__((nodebug))
+#else
+#define LLVM_ATTRIBUTE_NODEBUG
+#endif
+
 #if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0)
 #define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull))
 #elif defined(_MSC_VER)