Index: lib/CodeGen/LiveIntervalAnalysis.cpp
===================================================================
--- lib/CodeGen/LiveIntervalAnalysis.cpp
+++ lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -388,9 +388,11 @@
       if (!LiveOut.insert(Pred).second)
         continue;
       SlotIndex Stop = Indexes.getMBBEndIdx(Pred);
-      assert(OldRange.getVNInfoBefore(Stop) == VNI &&
-             "Wrong value out of predecessor");
-      WorkList.push_back(std::make_pair(Stop, VNI));
+      // The exit from a predecessor may be jointly dominated by undefs.
+      if (VNInfo *PVNI = OldRange.getVNInfoBefore(Stop)) {
+        assert(PVNI == VNI && "Wrong value out of predecessor");
+        WorkList.push_back(std::make_pair(Stop, VNI));
+      }
     }
   }
 }