diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -31529,7 +31529,9 @@
       AI->getParent() != I->getParent())
     return AtomicExpansionKind::CmpXChg;
 
-  assert(I->getOperand(0) == AI);
+  if (I->getOperand(0) != AI)
+    return AtomicExpansionKind::CmpXChg;
+
   // The following instruction must be a AND single bit.
   if (BitChange.second == ConstantBit || BitChange.second == NotConstantBit) {
     auto *C1 = dyn_cast<ConstantInt>(AI->getValOperand());