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diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
new file mode 100644
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+++ b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
@@ -0,0 +1,86 @@
+//===-- WebAssemblyPeephole.cpp - WebAssembly Peephole Optimiztions -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Late peephole optimizations for WebAssembly.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssembly.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-peephole"
+
+namespace {
+class WebAssemblyPeephole final : public MachineFunctionPass {
+  const char *getPassName() const override {
+    return "WebAssembly late peephole optimizer";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+public:
+  static char ID;
+  WebAssemblyPeephole() : MachineFunctionPass(ID) {}
+};
+} // end anonymous namespace
+
+char WebAssemblyPeephole::ID = 0;
+FunctionPass *llvm::createWebAssemblyPeephole() {
+  return new WebAssemblyPeephole();
+}
+
+bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) {
+  bool Changed = false;
+
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
+
+  for (auto &MBB : MF)
+    for (auto &MI : MBB)
+      switch (MI.getOpcode()) {
+      default:
+        break;
+      case WebAssembly::STORE8_I32:
+      case WebAssembly::STORE16_I32:
+      case WebAssembly::STORE8_I64:
+      case WebAssembly::STORE16_I64:
+      case WebAssembly::STORE32_I64:
+      case WebAssembly::STORE_F32:
+      case WebAssembly::STORE_F64:
+      case WebAssembly::STORE_I32:
+      case WebAssembly::STORE_I64: {
+        // Store instructions return their value operand. If we ended up using
+        // the same register for both, replace it with a dead def so that it
+        // can use $discard instead.
+        MachineOperand &MO = MI.getOperand(0);
+        unsigned OldReg = MO.getReg();
+        // TODO: Handle SP/physregs
+        if (OldReg == MI.getOperand(3).getReg()
+            && TargetRegisterInfo::isVirtualRegister(MI.getOperand(3).getReg())) {
+          Changed = true;
+          unsigned NewReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
+          MO.setReg(NewReg);
+          MO.setIsDead();
+          MFI.stackifyVReg(NewReg);
+          MFI.addWAReg(NewReg, WebAssemblyFunctionInfo::UnusedReg);
+        }
+      }
+      }
+
+  return Changed;
+}