Index: lib/Analysis/CaptureTracking.cpp
===================================================================
--- lib/Analysis/CaptureTracking.cpp
+++ lib/Analysis/CaptureTracking.cpp
@@ -271,6 +271,17 @@
           return;
       // Storing to the pointee does not cause the pointer to be captured.
       break;
+    case Instruction::AtomicRMW:
+    case Instruction::AtomicCmpXchg:
+      // atomicrmw and cmpxchg conceptually include both a load and store from
+      // the same location.  As with a store, the location being accessed is
+      // not captured, but the value being stored is.  (For cmpxchg, we
+      // probably don't need to capture the original comparison value, but for
+      // the moment, let's be conservative.)
+      if (V != I->getOperand(0))
+        if (Tracker->captured(U))
+          return;
+      break;
     case Instruction::BitCast:
     case Instruction::GetElementPtr:
     case Instruction::PHI:
Index: test/Transforms/FunctionAttrs/nocapture.ll
===================================================================
--- test/Transforms/FunctionAttrs/nocapture.ll
+++ test/Transforms/FunctionAttrs/nocapture.ll
@@ -193,3 +193,14 @@
   ret void
 }
 
+; CHECK: define void @test_cmpxchg(i32* nocapture %p)
+define void @test_cmpxchg(i32* %p) {
+  cmpxchg i32* %p, i32 0, i32 1 acquire monotonic
+  ret void
+}
+
+; CHECK: define void @test_atomicrmw(i32* nocapture %p)
+define void @test_atomicrmw(i32* %p) {
+  atomicrmw add i32* %p, i32 1 seq_cst
+  ret void
+}