diff --git a/llvm/include/llvm/Transforms/Scalar/MemCpyOptimizer.h b/llvm/include/llvm/Transforms/Scalar/MemCpyOptimizer.h
index 3e8a5bf6a5bd5..6c809bc881d05 100644
--- a/llvm/include/llvm/Transforms/Scalar/MemCpyOptimizer.h
+++ b/llvm/include/llvm/Transforms/Scalar/MemCpyOptimizer.h
@@ -83,7 +83,7 @@ class MemCpyOptPass : public PassInfoMixin<MemCpyOptPass> {
   bool moveUp(StoreInst *SI, Instruction *P, const LoadInst *LI);
   bool performStackMoveOptzn(Instruction *Load, Instruction *Store,
                              AllocaInst *DestAlloca, AllocaInst *SrcAlloca,
-                             uint64_t Size, BatchAAResults &BAA);
+                             TypeSize Size, BatchAAResults &BAA);
 
   void eraseInstruction(Instruction *I);
   bool iterateOnFunction(Function &F);
diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 4db9d1b6d309a..9c19c2973438c 100644
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -1428,7 +1428,7 @@ bool MemCpyOptPass::performMemCpyToMemSetOptzn(MemCpyInst *MemCpy,
 // allocas that aren't captured.
 bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
                                           AllocaInst *DestAlloca,
-                                          AllocaInst *SrcAlloca, uint64_t Size,
+                                          AllocaInst *SrcAlloca, TypeSize Size,
                                           BatchAAResults &BAA) {
   LLVM_DEBUG(dbgs() << "Stack Move: Attempting to optimize:\n"
                     << *Store << "\n");
@@ -1442,13 +1442,12 @@ bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
   // Check that copy is full with static size.
   const DataLayout &DL = DestAlloca->getModule()->getDataLayout();
   std::optional<TypeSize> SrcSize = SrcAlloca->getAllocationSize(DL);
-  if (!SrcSize || SrcSize->isScalable() || Size != SrcSize->getFixedValue()) {
+  if (!SrcSize || Size != *SrcSize) {
     LLVM_DEBUG(dbgs() << "Stack Move: Source alloca size mismatch\n");
     return false;
   }
   std::optional<TypeSize> DestSize = DestAlloca->getAllocationSize(DL);
-  if (!DestSize || DestSize->isScalable() ||
-      Size != DestSize->getFixedValue()) {
+  if (!DestSize || Size != *DestSize) {
     LLVM_DEBUG(dbgs() << "Stack Move: Destination alloca size mismatch\n");
     return false;
   }
@@ -1766,8 +1765,8 @@ bool MemCpyOptPass::processMemCpy(MemCpyInst *M, BasicBlock::iterator &BBI) {
   ConstantInt *Len = dyn_cast<ConstantInt>(M->getLength());
   if (Len == nullptr)
     return false;
-  if (performStackMoveOptzn(M, M, DestAlloca, SrcAlloca, Len->getZExtValue(),
-                            BAA)) {
+  if (performStackMoveOptzn(M, M, DestAlloca, SrcAlloca,
+                            TypeSize::getFixed(Len->getZExtValue()), BAA)) {
     // Avoid invalidating the iterator.
     BBI = M->getNextNonDebugInstruction()->getIterator();
     eraseInstruction(M);
diff --git a/llvm/test/Transforms/MemCpyOpt/stack-move.ll b/llvm/test/Transforms/MemCpyOpt/stack-move.ll
index dee630f470d00..6089c0a4d7cf5 100644
--- a/llvm/test/Transforms/MemCpyOpt/stack-move.ll
+++ b/llvm/test/Transforms/MemCpyOpt/stack-move.ll
@@ -113,6 +113,33 @@ define void @load_store() {
   ret void
 }
 
+; Test scalable vectors.
+define void @load_store_scalable(<vscale x 4 x i32> %x) {
+; CHECK-LABEL: define void @load_store_scalable
+; CHECK-SAME: (<vscale x 4 x i32> [[X:%.*]]) {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca <vscale x 4 x i32>, align 16
+; CHECK-NEXT:    store <vscale x 4 x i32> [[X]], ptr [[SRC]], align 16
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca <vscale x 4 x i32>
+  %dest = alloca <vscale x 4 x i32>
+  call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture %dest)
+  store <vscale x 4 x i32> %x, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  %src.val = load <vscale x 4 x i32>, ptr %src
+  store <vscale x 4 x i32> %src.val, ptr %dest
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+
+  call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture %dest)
+  ret void
+}
+
 ; Tests that merging two allocas shouldn't be more poisonous, smaller aligned src is valid.
 define void @align_up() {
 ; CHECK-LABEL: define void @align_up() {