Index: lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp
===================================================================
--- lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp
+++ lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp
@@ -29,48 +29,14 @@
 using namespace llvm;
 
 namespace {
-class WebAssemblyAsmBackendELF final : public MCAsmBackend {
-  bool Is64Bit;
-
-public:
-  explicit WebAssemblyAsmBackendELF(bool Is64Bit)
-      : MCAsmBackend(), Is64Bit(Is64Bit) {}
-  ~WebAssemblyAsmBackendELF() override {}
-
-  void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
-                  const MCValue &Target, MutableArrayRef<char> Data,
-                  uint64_t Value, bool IsPCRel) const override;
-
-  std::unique_ptr<MCObjectWriter>
-  createObjectWriter(raw_pwrite_stream &OS) const override;
-
-  // No instruction requires relaxation
-  bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
-                            const MCRelaxableFragment *DF,
-                            const MCAsmLayout &Layout) const override {
-    return false;
-  }
-
-  unsigned getNumFixupKinds() const override {
-    // We currently just use the generic fixups in MCFixup.h and don't have any
-    // target-specific fixups.
-    return 0;
-  }
-
-  bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
-
-  void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
-                        MCInst &Res) const override {}
-
-  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
-};
 
 class WebAssemblyAsmBackend final : public MCAsmBackend {
   bool Is64Bit;
+  bool IsELF;
 
 public:
-  explicit WebAssemblyAsmBackend(bool Is64Bit)
-      : MCAsmBackend(), Is64Bit(Is64Bit) {}
+  explicit WebAssemblyAsmBackend(bool Is64Bit, bool IsELF)
+      : MCAsmBackend(), Is64Bit(Is64Bit), IsELF(IsELF) {}
   ~WebAssemblyAsmBackend() override {}
 
   unsigned getNumFixupKinds() const override {
@@ -101,43 +67,6 @@
   bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
 };
 
-bool WebAssemblyAsmBackendELF::writeNopData(uint64_t Count,
-                                            MCObjectWriter *OW) const {
-  for (uint64_t i = 0; i < Count; ++i)
-    OW->write8(WebAssembly::Nop);
-
-  return true;
-}
-
-void WebAssemblyAsmBackendELF::applyFixup(const MCAssembler &Asm,
-                                          const MCFixup &Fixup,
-                                          const MCValue &Target,
-                                          MutableArrayRef<char> Data,
-                                          uint64_t Value, bool IsPCRel) const {
-  const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
-  assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
-
-  unsigned NumBytes = alignTo(Info.TargetSize, 8) / 8;
-  if (Value == 0)
-    return; // Doesn't change encoding.
-
-  // Shift the value into position.
-  Value <<= Info.TargetOffset;
-
-  unsigned Offset = Fixup.getOffset();
-  assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
-
-  // For each byte of the fragment that the fixup touches, mask in the
-  // bits from the fixup value.
-  for (unsigned i = 0; i != NumBytes; ++i)
-    Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff);
-}
-
-std::unique_ptr<MCObjectWriter>
-WebAssemblyAsmBackendELF::createObjectWriter(raw_pwrite_stream &OS) const {
-  return createWebAssemblyELFObjectWriter(OS, Is64Bit, 0);
-}
-
 const MCFixupKindInfo &
 WebAssemblyAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
   const static MCFixupKindInfo Infos[WebAssembly::NumTargetFixupKinds] = {
@@ -160,9 +89,6 @@
 
 bool WebAssemblyAsmBackend::writeNopData(uint64_t Count,
                                          MCObjectWriter *OW) const {
-  if (Count == 0)
-    return true;
-
   for (uint64_t i = 0; i < Count; ++i)
     OW->write8(WebAssembly::Nop);
 
@@ -195,12 +121,12 @@
 
 std::unique_ptr<MCObjectWriter>
 WebAssemblyAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
-  return createWebAssemblyWasmObjectWriter(OS, Is64Bit);
+  return IsELF ? createWebAssemblyELFObjectWriter(OS, Is64Bit, 0)
+               : createWebAssemblyWasmObjectWriter(OS, Is64Bit);
 }
+
 } // end anonymous namespace
 
 MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Triple &TT) {
-  if (TT.isOSBinFormatELF())
-    return new WebAssemblyAsmBackendELF(TT.isArch64Bit());
-  return new WebAssemblyAsmBackend(TT.isArch64Bit());
+  return new WebAssemblyAsmBackend(TT.isArch64Bit(), TT.isOSBinFormatELF());
 }