Index: lib/Transforms/Instrumentation/InstrProfiling.cpp
===================================================================
--- lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -147,9 +147,9 @@
   IRBuilder<> Builder(Inc->getParent(), *Inc);
   uint64_t Index = Inc->getIndex()->getZExtValue();
   Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
-  Value *Count = Builder.CreateLoad(Addr, "pgocount");
-  Count = Builder.CreateAdd(Count, Builder.getInt64(1));
-  Inc->replaceAllUsesWith(Builder.CreateStore(Count, Addr));
+  Builder.CreateAtomicRMW(AtomicRMWInst::Add, Addr, Builder.getInt64(1),
+                          llvm::Monotonic);
+  assert(Inc->use_empty() && "InstrProfIncrementInst has uses!");
   Inc->eraseFromParent();
 }