Index: lib/Transforms/Instrumentation/ThreadSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -358,7 +358,7 @@
   // (e.g. variables that do not escape, etc).
 
   // Instrument memory accesses.
-  if (ClInstrumentMemoryAccesses)
+  if (ClInstrumentMemoryAccesses && F.hasFnAttribute(Attribute::SanitizeThread))
     for (size_t i = 0, n = AllLoadsAndStores.size(); i < n; ++i) {
       Res |= instrumentLoadOrStore(AllLoadsAndStores[i]);
     }
Index: test/Instrumentation/ThreadSanitizer/no_sanitize_thread.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/no_sanitize_thread.ll
+++ test/Instrumentation/ThreadSanitizer/no_sanitize_thread.ll
@@ -0,0 +1,36 @@
+; RUN: opt < %s -tsan -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+; no sanitize_thread attribute here
+define i32 @read_4_bytes(i32* %a) {
+entry:
+  %tmp1 = load i32* %a, align 4
+  ret i32 %tmp1
+}
+
+; CHECK: define i32 @read_4_bytes(i32* %a) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT:   %tmp1 = load i32* %a, align 4
+; CHECK: ret i32 %tmp1
+
+; no sanitize_thread attribute here
+define i32 @read_4_bytes_and_call(i32* %a) {
+entry:
+  call void @foo()
+  %tmp1 = load i32* %a, align 4
+  ret i32 %tmp1
+}
+
+; CHECK: define i32 @read_4_bytes_and_call(i32* %a) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT:   %0 = call i8* @llvm.returnaddress(i32 0)
+; CHECK-NEXT:   call void @__tsan_func_entry(i8* %0)
+; CHECK-NEXT:   call void @foo()
+; CHECK-NEXT:   %tmp1 = load i32* %a, align 4
+; CHECK-NEXT:   call void @__tsan_func_exit()
+; CHECK-NEXT:   ret i32 %tmp1
+
+declare void @foo()
+
Index: test/Instrumentation/ThreadSanitizer/read_before_write.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/read_before_write.ll
+++ test/Instrumentation/ThreadSanitizer/read_before_write.ll
@@ -2,7 +2,7 @@
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
-define void @IncrementMe(i32* nocapture %ptr) nounwind uwtable {
+define void @IncrementMe(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
 entry:
   %0 = load i32* %ptr, align 4
   %inc = add nsw i32 %0, 1
@@ -14,7 +14,7 @@
 ; CHECK: __tsan_write
 ; CHECK: ret void
 
-define void @IncrementMeWithCallInBetween(i32* nocapture %ptr) nounwind uwtable {
+define void @IncrementMeWithCallInBetween(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
 entry:
   %0 = load i32* %ptr, align 4
   %inc = add nsw i32 %0, 1
Index: test/Instrumentation/ThreadSanitizer/read_from_global.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/read_from_global.ll
+++ test/Instrumentation/ThreadSanitizer/read_from_global.ll
@@ -4,7 +4,7 @@
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
 @const_global = external constant i32
-define i32 @read_from_const_global() nounwind uwtable readnone {
+define i32 @read_from_const_global() nounwind uwtable sanitize_thread readnone {
 entry:
   %0 = load i32* @const_global, align 4
   ret i32 %0
@@ -14,7 +14,7 @@
 ; CHECK: ret i32
 
 @non_const_global = global i32 0, align 4
-define i32 @read_from_non_const_global() nounwind uwtable readonly {
+define i32 @read_from_non_const_global() nounwind uwtable sanitize_thread readonly {
 entry:
   %0 = load i32* @non_const_global, align 4
   ret i32 %0
@@ -25,7 +25,7 @@
 ; CHECK: ret i32
 
 @const_global_array = external constant [10 x i32]
-define i32 @read_from_const_global_array(i32 %idx) nounwind uwtable readnone {
+define i32 @read_from_const_global_array(i32 %idx) nounwind uwtable sanitize_thread readnone {
 entry:
   %idxprom = sext i32 %idx to i64
   %arrayidx = getelementptr inbounds [10 x i32]* @const_global_array, i64 0, i64 %idxprom
@@ -38,7 +38,7 @@
 ; CHECK: ret i32
 
 %struct.Foo = type { i32 (...)** }
-define void @call_virtual_func(%struct.Foo* %f) uwtable {
+define void @call_virtual_func(%struct.Foo* %f) uwtable sanitize_thread {
 entry:
   %0 = bitcast %struct.Foo* %f to void (%struct.Foo*)***
   %vtable = load void (%struct.Foo*)*** %0, align 8, !tbaa !2
Index: test/Instrumentation/ThreadSanitizer/tsan_basic.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/tsan_basic.ll
+++ test/Instrumentation/ThreadSanitizer/tsan_basic.ll
@@ -3,7 +3,7 @@
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-unknown-linux-gnu"
 
-define i32 @read_4_bytes(i32* %a) {
+define i32 @read_4_bytes(i32* %a) sanitize_thread {
 entry:
   %tmp1 = load i32* %a, align 4
   ret i32 %tmp1
@@ -11,7 +11,7 @@
 
 ; CHECK: @llvm.global_ctors = {{.*}}@__tsan_init
 
-; CHECK: define i32 @read_4_bytes(i32* %a) {
+; CHECK: define i32 @read_4_bytes(i32* %a)
 ; CHECK:        call void @__tsan_func_entry(i8* %0)
 ; CHECK-NEXT:   %1 = bitcast i32* %a to i8*
 ; CHECK-NEXT:   call void @__tsan_read4(i8* %1)
Index: test/Instrumentation/ThreadSanitizer/vptr_read.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/vptr_read.ll
+++ test/Instrumentation/ThreadSanitizer/vptr_read.ll
@@ -2,7 +2,7 @@
 ; Check that vptr reads are treated in a special way.
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
-define i8 @Foo(i8* %a) nounwind uwtable {
+define i8 @Foo(i8* %a) nounwind uwtable sanitize_thread {
 entry:
 ; CHECK: call void @__tsan_vptr_read
   %0 = load i8* %a, align 8, !tbaa !0
Index: test/Instrumentation/ThreadSanitizer/vptr_update.ll
===================================================================
--- test/Instrumentation/ThreadSanitizer/vptr_update.ll
+++ test/Instrumentation/ThreadSanitizer/vptr_update.ll
@@ -2,7 +2,7 @@
 ; Check that vtable pointer updates are treated in a special way.
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
-define void @Foo(i8** nocapture %a, i8* %b) nounwind uwtable {
+define void @Foo(i8** nocapture %a, i8* %b) nounwind uwtable sanitize_thread {
 entry:
 ; CHECK: call void @__tsan_vptr_update
   store i8* %b, i8** %a, align 8, !tbaa !0