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diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyReplacePhysRegs.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyReplacePhysRegs.cpp
new file mode 100644
index 000000000000..5eafd6c54e78
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+++ b/llvm/lib/Target/WebAssembly/WebAssemblyReplacePhysRegs.cpp
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+//===-- WebAssemblyReplacePhysRegs.cpp - Replace phys regs with virt regs -===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements a pass that replaces physical registers with
+/// virtual registers.
+///
+/// LLVM expects certain physical registers, such as a stack pointer. However,
+/// WebAssembly doesn't actually have such physical registers. This pass is run
+/// once LLVM no longer needs these registers, and replaces them with virtual
+/// registers, so they can participate in register stackifying and coloring in
+/// the normal way.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssembly.h"
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblySubtarget.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-replace-phys-regs"
+
+namespace {
+class WebAssemblyReplacePhysRegs final : public MachineFunctionPass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  WebAssemblyReplacePhysRegs() : MachineFunctionPass(ID) {}
+
+private:
+  StringRef getPassName() const override {
+    return "WebAssembly Replace Physical Registers";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+} // end anonymous namespace
+
+char WebAssemblyReplacePhysRegs::ID = 0;
+INITIALIZE_PASS(WebAssemblyReplacePhysRegs, DEBUG_TYPE,
+                "Replace physical registers with virtual registers", false,
+                false)
+
+FunctionPass *llvm::createWebAssemblyReplacePhysRegs() {
+  return new WebAssemblyReplacePhysRegs();
+}
+
+bool WebAssemblyReplacePhysRegs::runOnMachineFunction(MachineFunction &MF) {
+  LLVM_DEBUG({
+    dbgs() << "********** Replace Physical Registers **********\n"
+           << "********** Function: " << MF.getName() << '\n';
+  });
+
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  const auto &TRI = *MF.getSubtarget<WebAssemblySubtarget>().getRegisterInfo();
+  bool Changed = false;
+
+  assert(!mustPreserveAnalysisID(LiveIntervalsID) &&
+         "LiveIntervals shouldn't be active yet!");
+  // We don't preserve SSA or liveness.
+  MRI.leaveSSA();
+  MRI.invalidateLiveness();
+
+  for (unsigned PReg = WebAssembly::NoRegister + 1;
+       PReg < WebAssembly::NUM_TARGET_REGS; ++PReg) {
+    // Skip fake registers that are never used explicitly.
+    if (PReg == WebAssembly::VALUE_STACK || PReg == WebAssembly::ARGUMENTS)
+      continue;
+
+    // Replace explicit uses of the physical register with a virtual register.
+    const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(PReg);
+    unsigned VReg = WebAssembly::NoRegister;
+    for (auto I = MRI.reg_begin(PReg), E = MRI.reg_end(); I != E;) {
+      MachineOperand &MO = *I++;
+      if (!MO.isImplicit()) {
+        if (VReg == WebAssembly::NoRegister)
+          VReg = MRI.createVirtualRegister(RC);
+        MO.setReg(VReg);
+        if (MO.getParent()->isDebugValue())
+          MO.setIsDebug();
+        Changed = true;
+      }
+    }
+  }
+
+  return Changed;
+}