Index: lib/Transforms/Utils/PromoteMemoryToRegister.cpp
===================================================================
--- lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -509,6 +509,9 @@
           !isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
         addAssumeNonNull(AC, LI);
 
+      // we have a loop, bail out
+      if (LI == ReplVal)
+        return false;
       LI->replaceAllUsesWith(ReplVal);
     }