Index: llvm/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2269,7 +2269,7 @@
 
       // Register the new instruction with the assumption cache if necessary.
       if (auto *II = dyn_cast_or_null<IntrinsicInst>(N))
-        if (II->getIntrinsicID() == Intrinsic::assume)
+        if (AC && II->getIntrinsicID() == Intrinsic::assume)
           AC->registerAssumption(II);
     }