diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp
index cfb8b7e7dcb55edede6140452efdec4480d02123..da2d0f81748593ac5bae5fedd0e1531ad66e7cb1 100644
--- a/llvm/lib/Analysis/MemorySSA.cpp
+++ b/llvm/lib/Analysis/MemorySSA.cpp
@@ -1229,6 +1229,7 @@ MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT)
   // safe because there are no CFG changes while building MemorySSA and can
   // significantly reduce the time spent by the compiler in AA, because we will
   // make queries about all the instructions in the Function.
+  assert(AA && "No alias analysis?");
   BatchAAResults BatchAA(*AA);
   buildMemorySSA(BatchAA);
   // Intentionally leave AA to nullptr while building so we don't accidently