Index: lib/Analysis/MemorySSAUpdater.cpp
===================================================================
--- lib/Analysis/MemorySSAUpdater.cpp
+++ lib/Analysis/MemorySSAUpdater.cpp
@@ -125,11 +125,10 @@
     } else {
       // Otherwise, have to walk the all access iterator.
       auto Iter = MA->getReverseIterator();
-      ++Iter;
       while (&*Iter != &*Defs->begin()) {
-        if (!isa<MemoryUse>(*Iter))
-          return &*Iter;
         --Iter;
+        if (!isa<MemoryUse>(*Iter))
+          return nullptr;
       }
       // At this point it must be pointing at firstdef
       assert(&*Iter == &*Defs->begin() &&