diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index c0d69f9..e34bf6f 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -660,6 +660,10 @@
   APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
 
   V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds);
+  // As that strip may trace through `addrspacecast`, need to sext or trunc
+  // the offset calculated.
+  IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
+  Offset = Offset.sextOrTrunc(IntPtrTy->getIntegerBitWidth());
 
   Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
   if (V->getType()->isVectorTy())