diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 9a55c08..0b1ddc1 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -102,9 +102,10 @@
   if (LangOpts.CUDA)
     createCUDARuntime();
 
-  // Enable TBAA unless it's suppressed.
-  if (!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0)
-    TBAA = new CodeGenTBAA(Context, VMContext, getLangOpts(),
+  // Enable TBAA unless it's suppressed. ThreadSanitizer needs TBAA even at O0.
+  if (LangOpts.ThreadSanitizer ||
+      (!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0))
+    TBAA = new CodeGenTBAA(Context, VMContext, CodeGenOpts, getLangOpts(),
                            ABI.getMangleContext());
 
   // If debug info or coverage generation is enabled, create the CGDebugInfo
diff --git a/lib/CodeGen/CodeGenTBAA.cpp b/lib/CodeGen/CodeGenTBAA.cpp
index a3cadcf..e9164dc 100644
--- a/lib/CodeGen/CodeGenTBAA.cpp
+++ b/lib/CodeGen/CodeGenTBAA.cpp
@@ -18,6 +18,7 @@
 #include "CodeGenTBAA.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Mangle.h"
+#include "clang/Frontend/CodeGenOptions.h"
 #include "llvm/LLVMContext.h"
 #include "llvm/Metadata.h"
 #include "llvm/Constants.h"
@@ -26,8 +27,10 @@
 using namespace CodeGen;
 
 CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
+                         const CodeGenOptions &CGO,
                          const LangOptions &Features, MangleContext &MContext)
-  : Context(Ctx), VMContext(VMContext), Features(Features), MContext(MContext),
+  : Context(Ctx), VMContext(VMContext), CodeGenOpts(CGO),
+    Features(Features), MContext(MContext),
     MDHelper(VMContext), Root(0), Char(0) {
 }
 
@@ -74,6 +77,10 @@
 
 llvm::MDNode *
 CodeGenTBAA::getTBAAInfo(QualType QTy) {
+  // At -O0 TBAA is not emitted for regular types.
+  if (CodeGenOpts.OptimizationLevel == 0 || CodeGenOpts.RelaxedAliasing)
+    return NULL;
+
   // If the type has the may_alias attribute (even on a typedef), it is
   // effectively in the general char alias class.
   if (TypeHasMayAlias(QTy))
diff --git a/lib/CodeGen/CodeGenTBAA.h b/lib/CodeGen/CodeGenTBAA.h
index 4a97852..9463b61 100644
--- a/lib/CodeGen/CodeGenTBAA.h
+++ b/lib/CodeGen/CodeGenTBAA.h
@@ -26,6 +26,7 @@
 
 namespace clang {
   class ASTContext;
+  class CodeGenOptions;
   class LangOptions;
   class MangleContext;
   class QualType;
@@ -39,6 +40,7 @@
 class CodeGenTBAA {
   ASTContext &Context;
   llvm::LLVMContext& VMContext;
+  const CodeGenOptions &CodeGenOpts;
   const LangOptions &Features;
   MangleContext &MContext;
 
@@ -61,6 +63,7 @@
 
 public:
   CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext &VMContext,
+              const CodeGenOptions &CGO,
               const LangOptions &Features,
               MangleContext &MContext);
   ~CodeGenTBAA();