Index: lib/CodeGen/CGBuilder.h
===================================================================
--- lib/CodeGen/CGBuilder.h
+++ lib/CodeGen/CGBuilder.h
@@ -22,9 +22,7 @@
 /// \brief This is an IRBuilder insertion helper that forwards to
 /// CodeGenFunction::InsertHelper, which adds necessary metadata to
 /// instructions.
-template <bool PreserveNames>
-class CGBuilderInserter
-    : protected llvm::IRBuilderDefaultInserter<PreserveNames> {
+class CGBuilderInserter : protected llvm::IRBuilderDefaultInserter {
 public:
   CGBuilderInserter() = default;
   explicit CGBuilderInserter(CodeGenFunction *CGF) : CGF(CGF) {}
@@ -38,17 +36,10 @@
   CodeGenFunction *CGF = nullptr;
 };
 
-// Don't preserve names on values in an optimized build.
-#ifdef NDEBUG
-#define PreserveNames false
-#else
-#define PreserveNames true
-#endif
-
-typedef CGBuilderInserter<PreserveNames> CGBuilderInserterTy;
+typedef CGBuilderInserter CGBuilderInserterTy;
 
-typedef llvm::IRBuilder<PreserveNames, llvm::ConstantFolder,
-                        CGBuilderInserterTy> CGBuilderBaseTy;
+typedef llvm::IRBuilder<llvm::ConstantFolder, CGBuilderInserterTy>
+    CGBuilderBaseTy;
 
 class CGBuilderTy : public CGBuilderBaseTy {
   /// Storing a reference to the type cache here makes it a lot easier
@@ -298,8 +289,6 @@
   }
 };
 
-#undef PreserveNames
-
 }  // end namespace CodeGen
 }  // end namespace clang
 
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -3605,7 +3605,7 @@
   }
 
   llvm::Instruction *CI = CS.getInstruction();
-  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
+  if (!CI->getType()->isVoidTy())
     CI->setName("call");
 
   // Emit any writebacks immediately.  Arguably this should happen
Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -66,8 +66,6 @@
 /// block.
 llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(llvm::Type *Ty,
                                                     const Twine &Name) {
-  if (!Builder.isNamePreserving())
-    return new llvm::AllocaInst(Ty, nullptr, "", AllocaInsertPt);
   return new llvm::AllocaInst(Ty, nullptr, Name, AllocaInsertPt);
 }
 
Index: lib/CodeGen/CodeGenAction.cpp
===================================================================
--- lib/CodeGen/CodeGenAction.cpp
+++ lib/CodeGen/CodeGenAction.cpp
@@ -656,7 +656,13 @@
 
 CodeGenAction::CodeGenAction(unsigned _Act, LLVMContext *_VMContext)
     : Act(_Act), VMContext(_VMContext ? _VMContext : new LLVMContext),
-      OwnsVMContext(!_VMContext) {}
+      OwnsVMContext(!_VMContext) {
+#ifdef NDEBUG
+  // FIXME: change this to be controlled by a cc1 flag that the driver passes,
+  // on the model of --disable-free
+  _VMContext.setDiscardValueNames(true);
+#endif
+}
 
 CodeGenAction::~CodeGenAction() {
   TheModule.reset();
Index: lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- lib/CodeGen/CodeGenFunction.cpp
+++ lib/CodeGen/CodeGenFunction.cpp
@@ -747,9 +747,7 @@
   // later.  Don't create this with the builder, because we don't want it
   // folded.
   llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
-  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
-  if (Builder.isNamePreserving())
-    AllocaInsertPt->setName("allocapt");
+  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "allocapt", EntryBB);
 
   ReturnBlock = getJumpDestInCurrentScope("return");
 
@@ -1862,26 +1860,14 @@
     CGM.getSanitizerMetadata()->disableSanitizerForInstruction(I);
 }
 
-template <bool PreserveNames>
-void CGBuilderInserter<PreserveNames>::InsertHelper(
+void CGBuilderInserter::InsertHelper(
     llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB,
     llvm::BasicBlock::iterator InsertPt) const {
-  llvm::IRBuilderDefaultInserter<PreserveNames>::InsertHelper(I, Name, BB,
-                                                              InsertPt);
+  llvm::IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
   if (CGF)
     CGF->InsertHelper(I, Name, BB, InsertPt);
 }
 
-#ifdef NDEBUG
-#define PreserveNames false
-#else
-#define PreserveNames true
-#endif
-template void CGBuilderInserter<PreserveNames>::InsertHelper(
-    llvm::Instruction *I, const llvm::Twine &Name, llvm::BasicBlock *BB,
-    llvm::BasicBlock::iterator InsertPt) const;
-#undef PreserveNames
-
 static bool hasRequiredFeatures(const SmallVectorImpl<StringRef> &ReqFeatures,
                                 CodeGenModule &CGM, const FunctionDecl *FD,
                                 std::string &FirstMissing) {