diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 56900a6..d8c63a4 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -186,6 +186,7 @@
   case Intrinsic::riscv_masked_atomicrmw_min_i32:
   case Intrinsic::riscv_masked_atomicrmw_umax_i32:
   case Intrinsic::riscv_masked_atomicrmw_umin_i32:
+  case Intrinsic::riscv_masked_cmpxchg_i32:
     PointerType *PtrTy = cast<PointerType>(I.getArgOperand(0)->getType());
     Info.opc = ISD::INTRINSIC_W_CHAIN;
     Info.memVT = MVT::getVT(PtrTy->getElementType());
@@ -1708,3 +1709,23 @@
 
   return Builder.CreateCall(LrwOpScwLoop, {AlignedAddr, Incr, Mask, Ordering});
 }
+
+TargetLowering::AtomicExpansionKind
+RISCVTargetLowering::shouldExpandAtomicCmpXchgInIR(
+    AtomicCmpXchgInst *CI) const {
+  unsigned Size = CI->getCompareOperand()->getType()->getPrimitiveSizeInBits();
+  if (Size == 8 || Size == 16)
+    return AtomicExpansionKind::MaskedIntrinsic;
+  return AtomicExpansionKind::None;
+}
+
+Value *RISCVTargetLowering::emitMaskedAtomicCmpXchgIntrinsic(
+    IRBuilder<> &Builder, AtomicCmpXchgInst *CI, Value *AlignedAddr,
+    Value *CmpVal, Value *NewVal, Value *Mask, AtomicOrdering Ord) const {
+  Value *Ordering = Builder.getInt32(static_cast<uint32_t>(Ord));
+  Type *Tys[] = {AlignedAddr->getType()};
+  Function *MaskedCmpXchg = Intrinsic::getDeclaration(
+      CI->getModule(), Intrinsic::riscv_masked_cmpxchg_i32, Tys);
+  return Builder.CreateCall(MaskedCmpXchg,
+                            {AlignedAddr, CmpVal, NewVal, Mask, Ordering});
+}