diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -384,6 +384,10 @@
     SDValue replaceStoreOfFPConstant(StoreSDNode *ST);
 
     SDValue visitSTORE(SDNode *N);
+
+    SDValue ImproveLifetimeNodeChain(SDNode *N);
+
+    SDValue visitLIFETIME_START(SDNode *N);
     SDValue visitLIFETIME_END(SDNode *N);
     SDValue visitINSERT_VECTOR_ELT(SDNode *N);
     SDValue visitEXTRACT_VECTOR_ELT(SDNode *N);
@@ -1592,6 +1596,8 @@
   case ISD::MLOAD:              return visitMLOAD(N);
   case ISD::MSCATTER:           return visitMSCATTER(N);
   case ISD::MSTORE:             return visitMSTORE(N);
+  case ISD::LIFETIME_START:
+    return visitLIFETIME_START(N);
   case ISD::LIFETIME_END:       return visitLIFETIME_END(N);
   case ISD::FP_TO_FP16:         return visitFP_TO_FP16(N);
   case ISD::FP16_TO_FP:         return visitFP16_TO_FP(N);
@@ -15569,7 +15575,32 @@
   return ReduceLoadOpStoreWidth(N);
 }
 
+SDValue DAGCombiner::ImproveLifetimeNodeChain(SDNode *N) {
+  auto Chain = N->getOperand(0);
+  auto NewChain = FindBetterChain(N, Chain);
+  if (NewChain != Chain) {
+    SDNode *N2 = DAG.UpdateNodeOperands(N, NewChain, N->getOperand(1));
+    // Make sure users of new N still depend on Chain
+    auto TF = DAG.getNode(ISD::TokenFactor, SDLoc(N2), MVT::Other, Chain,
+                          SDValue(N2, 0));
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N2, 0), TF);
+    AddToWorklist(DAG.UpdateNodeOperands(TF.getNode(), Chain, SDValue(N2, 0)));
+    AddToWorklist(N2);
+    return SDValue(N, 0);
+  }
+  return SDValue();
+}
+
+SDValue DAGCombiner::visitLIFETIME_START(SDNode *N) {
+  if (SDValue V = ImproveLifetimeNodeChain(N))
+    return V;
+  return SDValue();
+}
+
 SDValue DAGCombiner::visitLIFETIME_END(SDNode *N) {
+  if (SDValue V = ImproveLifetimeNodeChain(N))
+    return V;
+
   const auto *LifetimeEnd = cast<LifetimeSDNode>(N);
   if (!LifetimeEnd->hasOffset())
     return SDValue();
@@ -15580,12 +15611,10 @@
   // We walk up the chains to find stores.
   SmallVector<SDValue, 8> Chains = {N->getOperand(0)};
   while (!Chains.empty()) {
-    SDValue Chain = Chains.back();
-    Chains.pop_back();
-    if (!Chain.hasOneUse())
-      continue;
+    SDValue Chain = Chains.pop_back_val();
     switch (Chain.getOpcode()) {
     case ISD::TokenFactor:
+      AddToWorklist(Chain.getNode());
       for (unsigned Nops = Chain.getNumOperands(); Nops;)
         Chains.push_back(Chain.getOperand(--Nops));
       break;
@@ -15609,6 +15638,7 @@
                    dbgs() << "\nwithin LIFETIME_END of : ";
                    LifetimeEndBase.dump(); dbgs() << "\n");
         CombineTo(ST, ST->getChain());
+        AddToWorklist(N);
         return SDValue(N, 0);
       }
     }
diff --git a/llvm/test/CodeGen/X86/swap.ll b/llvm/test/CodeGen/X86/swap.ll
--- a/llvm/test/CodeGen/X86/swap.ll
+++ b/llvm/test/CodeGen/X86/swap.ll
@@ -87,14 +87,12 @@
 ; NOAA-LABEL: twoallocs:
 ; NOAA:       # %bb.0: # %entry
 ; NOAA-NEXT:    vmovups (%rdi), %xmm0
-; NOAA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; NOAA-NEXT:    vmovups %xmm0, (%rsi)
 ; NOAA-NEXT:    retq
 ;
 ; AA-LABEL: twoallocs:
 ; AA:       # %bb.0: # %entry
 ; AA-NEXT:    vmovups (%rdi), %xmm0
-; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rsi)
 ; AA-NEXT:    retq
 entry:
@@ -115,20 +113,13 @@
 define dso_local void @onealloc_readback_1(i8* nocapture %a, i8* nocapture %b) local_unnamed_addr {
 ; NOAA-LABEL: onealloc_readback_1:
 ; NOAA:       # %bb.0: # %entry
-; NOAA-NEXT:    vmovups (%rdi), %xmm0
-; NOAA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; NOAA-NEXT:    vmovups (%rsi), %xmm0
-; NOAA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
-; NOAA-NEXT:    vmovaps -{{[0-9]+}}(%rsp), %xmm0
 ; NOAA-NEXT:    vmovups %xmm0, (%rdi)
 ; NOAA-NEXT:    retq
 ;
 ; AA-LABEL: onealloc_readback_1:
 ; AA:       # %bb.0: # %entry
-; AA-NEXT:    vmovups (%rdi), %xmm0
-; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups (%rsi), %xmm0
-; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rdi)
 ; AA-NEXT:    retq
 entry:
@@ -148,20 +139,13 @@
 define dso_local void @onealloc_readback_2(i8* nocapture %a, i8* nocapture %b) local_unnamed_addr {
 ; NOAA-LABEL: onealloc_readback_2:
 ; NOAA:       # %bb.0: # %entry
-; NOAA-NEXT:    vmovups (%rdi), %xmm0
-; NOAA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; NOAA-NEXT:    vmovups (%rsi), %xmm0
-; NOAA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
-; NOAA-NEXT:    vmovaps -{{[0-9]+}}(%rsp), %xmm0
 ; NOAA-NEXT:    vmovups %xmm0, (%rdi)
 ; NOAA-NEXT:    retq
 ;
 ; AA-LABEL: onealloc_readback_2:
 ; AA:       # %bb.0: # %entry
-; AA-NEXT:    vmovups (%rdi), %xmm0
-; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups (%rsi), %xmm0
-; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rdi)
 ; AA-NEXT:    retq
 entry: