Index: include/llvm/ProfileData/InstrProf.h
===================================================================
--- include/llvm/ProfileData/InstrProf.h
+++ include/llvm/ProfileData/InstrProf.h
@@ -235,6 +235,9 @@
                               InstrProfValueData ValueData[],
                               uint32_t &ActualNumValueData, uint64_t &TotalC);
 
+/// Checks if the provided Value is an address of the profiler counter.
+bool isAddressOfProfileCounter(Value *Addr);
+
 const std::error_category &instrprof_category();
 
 enum class instrprof_error {
Index: lib/ProfileData/InstrProf.cpp
===================================================================
--- lib/ProfileData/InstrProf.cpp
+++ lib/ProfileData/InstrProf.cpp
@@ -14,6 +14,7 @@
 
 #include "llvm/ProfileData/InstrProf.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalVariable.h"
@@ -248,6 +249,25 @@
   return 0;
 }
 
+bool isAddressOfProfileCounter(Value *Addr) {
+  // If this is a GEPCE, just analyze its pointer operand.
+  const ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
+  if (CE && CE->getOpcode() == Instruction::GetElementPtr)
+      Addr = CE->getOperand(0);
+
+  // Check if global the address is pointing to is in the
+  // PGO counters section.
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
+    if (GV->hasSection()) {
+      Triple T = Triple(GV->getParent()->getTargetTriple());
+      bool isMachO = T.isOSBinFormatMachO();
+      if (getInstrProfCountersSectionName(isMachO).equals(GV->getSection()))
+        return false;
+    }
+  }
+  return true;
+}
+
 instrprof_error InstrProfValueSiteRecord::merge(InstrProfValueSiteRecord &Input,
                                                 uint64_t Weight) {
   this->sortByTargetValues();
Index: lib/Transforms/Instrumentation/ThreadSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -36,6 +36,7 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
+#include "llvm/ProfileData/InstrProf.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MathExtras.h"
@@ -285,10 +286,21 @@
        E = Local.rend(); It != E; ++It) {
     Instruction *I = *It;
     if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
-      WriteTargets.insert(Store->getPointerOperand());
+      Value *Addr = Store->getPointerOperand();
+      if (!isAddressOfProfileCounter(Addr)) {
+        // We should not instrument globals from instruction profiler counters
+        // since they contain known races.
+        continue;
+      }
+      WriteTargets.insert(Addr);
     } else {
       LoadInst *Load = cast<LoadInst>(I);
       Value *Addr = Load->getPointerOperand();
+      if (!isAddressOfProfileCounter(Addr)) {
+        // We should not instrument globals from instruction profiler counters
+        // since they contain known races.
+        continue;
+      }
       if (WriteTargets.count(Addr)) {
         // We will write to this temp, so no reason to analyze the read.
         NumOmittedReadsBeforeWrite++;
Index: test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll
===================================================================
--- /dev/null
+++ test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll
@@ -0,0 +1,21 @@
+; This test checks that we are not instrumenting unnecessary (and unwanted)
+; acesses to globals:
+; - Instruction profiler counter instrumentation has known intended races.
+;
+; RUN: opt < %s -tsan -S | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9"
+
+@__profc_foo = private global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
+
+define i32 @foo() sanitize_thread {
+entry:
+  %pgocount = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo, i64 0, i64 0)
+  %0 = add i64 %pgocount, 1
+  store i64 %0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo, i64 0, i64 0)
+  ret i32 1
+}
+
+; CHECK-NOT: {{call void @__tsan_write}}
+; CHECK: __tsan_init