Index: lib/Analysis/BasicAliasAnalysis.cpp
===================================================================
--- lib/Analysis/BasicAliasAnalysis.cpp
+++ lib/Analysis/BasicAliasAnalysis.cpp
@@ -1526,6 +1526,9 @@
   if (!Inst)
     return true;
 
+  if (VisitedPhiBBs.empty())
+    return true;
+
   if (VisitedPhiBBs.size() > MaxNumPhiBBsValueReachabilityCheck)
     return false;