diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -171,6 +171,17 @@
 
   void emitConstantPools() override;
 
+  virtual void emitARMWinCFIAllocStack(unsigned Size, bool Wide);
+  virtual void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide);
+  virtual void emitARMWinCFISaveSP(unsigned Reg);
+  virtual void emitARMWinCFISaveFRegs(unsigned First, unsigned Last);
+  virtual void emitARMWinCFISaveLR(unsigned Offset);
+  virtual void emitARMWinCFIPrologEnd(bool Fragment);
+  virtual void emitARMWinCFINop(bool Wide);
+  virtual void emitARMWinCFIEpilogStart(unsigned Condition);
+  virtual void emitARMWinCFIEpilogEnd();
+  virtual void emitARMWinCFICustom(unsigned Opcode);
+
   /// Reset any state between object emissions, i.e. the equivalent of
   /// MCStreamer's reset method.
   virtual void reset();
diff --git a/llvm/include/llvm/MC/MCWin64EH.h b/llvm/include/llvm/MC/MCWin64EH.h
--- a/llvm/include/llvm/MC/MCWin64EH.h
+++ b/llvm/include/llvm/MC/MCWin64EH.h
@@ -57,13 +57,19 @@
                       bool HandlerData) const override;
 };
 
-class ARM64UnwindEmitter : public WinEH::UnwindEmitter {
+class ARMUnwindEmitter : public WinEH::UnwindEmitter {
 public:
   void Emit(MCStreamer &Streamer) const override;
   void EmitUnwindInfo(MCStreamer &Streamer, WinEH::FrameInfo *FI,
                       bool HandlerData) const override;
 };
 
+class ARM64UnwindEmitter : public WinEH::UnwindEmitter {
+public:
+  void Emit(MCStreamer &Streamer) const override;
+  void EmitUnwindInfo(MCStreamer &Streamer, WinEH::FrameInfo *FI,
+                      bool HandlerData) const override;
+};
 }
 } // end namespace llvm
 
diff --git a/llvm/include/llvm/MC/MCWinEH.h b/llvm/include/llvm/MC/MCWinEH.h
--- a/llvm/include/llvm/MC/MCWinEH.h
+++ b/llvm/include/llvm/MC/MCWinEH.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_MC_MCWINEH_H
 #define LLVM_MC_MCWINEH_H
 
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
 #include <vector>
 
@@ -50,12 +51,14 @@
   bool HandlesUnwind = false;
   bool HandlesExceptions = false;
   bool EmitAttempted = false;
+  bool Fragment = false;
 
   int LastFrameInst = -1;
   const FrameInfo *ChainedParent = nullptr;
   std::vector<Instruction> Instructions;
   struct Epilog {
     std::vector<Instruction> Instructions;
+    unsigned Condition;
   };
   MapVector<MCSymbol *, Epilog> EpilogMap;
 
diff --git a/llvm/include/llvm/Support/Win64EH.h b/llvm/include/llvm/Support/Win64EH.h
--- a/llvm/include/llvm/Support/Win64EH.h
+++ b/llvm/include/llvm/Support/Win64EH.h
@@ -24,6 +24,9 @@
 /// UnwindOpcodes - Enumeration whose values specify a single operation in
 /// the prolog of a function.
 enum UnwindOpcodes {
+  // The following set of unwind opcodes is for x86_64.  They are documented at
+  // https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64.
+  // Some generic values from this set are used for other architectures too.
   UOP_PushNonVol = 0,
   UOP_AllocLarge,
   UOP_AllocSmall,
@@ -57,7 +60,38 @@
   UOP_SaveNext,
   UOP_TrapFrame,
   UOP_Context,
-  UOP_ClearUnwoundToCall
+  UOP_ClearUnwoundToCall,
+  // The following set of unwind opcodes is for ARM.  They are documented at
+  // https://docs.microsoft.com/en-us/cpp/build/arm-exception-handling
+
+  // Stack allocations use UOP_AllocSmall, UOP_AllocLarge from above, plus
+  // the following. AllocSmall, AllocLarge and AllocHuge represent a 16 bit
+  // instruction, while the WideAlloc* opcodes represent a 32 bit instruction.
+  // Small can represent a stack offset of 0x7f*4 (252) bytes, Medium can
+  // represent up to 0x3ff*4 (4092) bytes, Large up to 0xffff*4 (262140) bytes,
+  // and Huge up to 0xffffff*4 (67108860) bytes.
+  UOP_AllocHuge,
+  UOP_WideAllocMedium,
+  UOP_WideAllocLarge,
+  UOP_WideAllocHuge,
+
+  UOP_WideSaveRegMask,
+  UOP_SaveSP,
+  UOP_SaveRegsR4R7LR,
+  UOP_WideSaveRegsR4R11LR,
+  UOP_SaveFRegD8D15,
+  UOP_SaveRegMask,
+  UOP_SaveLR,
+  UOP_SaveFRegD0D15,
+  UOP_SaveFRegD16D31,
+  // Using UOP_Nop from above
+  UOP_WideNop,
+  // Using UOP_End from above
+  UOP_EndNop,
+  UOP_WideEndNop,
+  // A custom unspecified opcode, consisting of one or more bytes. This
+  // allows producing opcodes in the implementation defined/reserved range.
+  UOP_Custom,
 };
 
 /// UnwindCode - This union describes a single operation in a function prolog,
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -693,7 +693,8 @@
   }
 
   int UnwindHelpOffset = 0;
-  if (Asm->MAI->usesWindowsCFI())
+  if (Asm->MAI->usesWindowsCFI() &&
+      FuncInfo.UnwindHelpFrameIdx != std::numeric_limits<int>::max())
     UnwindHelpOffset =
         getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx, FuncInfo);
 
@@ -755,7 +756,8 @@
   AddComment("IPToStateXData");
   OS.emitValue(create32bitRef(IPToStateXData), 4);
 
-  if (Asm->MAI->usesWindowsCFI()) {
+  if (Asm->MAI->usesWindowsCFI() &&
+      FuncInfo.UnwindHelpFrameIdx != std::numeric_limits<int>::max()) {
     AddComment("UnwindHelp");
     OS.emitInt32(UnwindHelpOffset);
   }
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -2069,10 +2069,14 @@
 
   OS << "\t.seh_handler ";
   Sym->print(OS, MAI);
+  char Marker = '@';
+  const Triple &T = getContext().getTargetTriple();
+  if (T.getArch() == Triple::arm || T.getArch() == Triple::thumb)
+    Marker = '%';
   if (Unwind)
-    OS << ", @unwind";
+    OS << ", " << Marker << "unwind";
   if (Except)
-    OS << ", @except";
+    OS << ", " << Marker << "except";
   EmitEOL();
 }
 
diff --git a/llvm/lib/MC/MCParser/COFFAsmParser.cpp b/llvm/lib/MC/MCParser/COFFAsmParser.cpp
--- a/llvm/lib/MC/MCParser/COFFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/COFFAsmParser.cpp
@@ -699,8 +699,8 @@
 
 bool COFFAsmParser::ParseAtUnwindOrAtExcept(bool &unwind, bool &except) {
   StringRef identifier;
-  if (getLexer().isNot(AsmToken::At))
-    return TokError("a handler attribute must begin with '@'");
+  if (getLexer().isNot(AsmToken::At) && getLexer().isNot(AsmToken::Percent))
+    return TokError("a handler attribute must begin with '@' or '%'");
   SMLoc startLoc = getLexer().getLoc();
   Lex();
   if (getParser().parseIdentifier(identifier))
diff --git a/llvm/lib/MC/MCWin64EH.cpp b/llvm/lib/MC/MCWin64EH.cpp
--- a/llvm/lib/MC/MCWin64EH.cpp
+++ b/llvm/lib/MC/MCWin64EH.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/MCWin64EH.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
@@ -250,8 +251,21 @@
   ::EmitUnwindInfo(Streamer, info);
 }
 
-static int64_t GetAbsDifference(MCStreamer &Streamer, const MCSymbol *LHS,
-                                const MCSymbol *RHS) {
+static const MCExpr *GetSubDivExpr(MCStreamer &Streamer, const MCSymbol *LHS,
+                                   const MCSymbol *RHS, int Div) {
+  MCContext &Context = Streamer.getContext();
+  const MCExpr *Expr =
+      MCBinaryExpr::createSub(MCSymbolRefExpr::create(LHS, Context),
+                              MCSymbolRefExpr::create(RHS, Context), Context);
+  if (Div != 1)
+    Expr = MCBinaryExpr::createDiv(Expr, MCConstantExpr::create(Div, Context),
+                                   Context);
+  return Expr;
+}
+
+static Optional<int64_t> GetOptionalAbsDifference(MCStreamer &Streamer,
+                                                  const MCSymbol *LHS,
+                                                  const MCSymbol *RHS) {
   MCContext &Context = Streamer.getContext();
   const MCExpr *Diff =
       MCBinaryExpr::createSub(MCSymbolRefExpr::create(LHS, Context),
@@ -262,10 +276,18 @@
   // unusual constructs, like an inline asm with an alignment directive.
   int64_t value;
   if (!Diff->evaluateAsAbsolute(value, OS->getAssembler()))
-    report_fatal_error("Failed to evaluate function length in SEH unwind info");
+    return None;
   return value;
 }
 
+static int64_t GetAbsDifference(MCStreamer &Streamer, const MCSymbol *LHS,
+                                const MCSymbol *RHS) {
+  Optional<int64_t> MaybeDiff = GetOptionalAbsDifference(Streamer, LHS, RHS);
+  if (!MaybeDiff)
+    report_fatal_error("Failed to evaluate function length in SEH unwind info");
+  return *MaybeDiff;
+}
+
 static uint32_t ARM64CountOfUnwindCodes(ArrayRef<WinEH::Instruction> Insns) {
   uint32_t Count = 0;
   for (const auto &I : Insns) {
@@ -1102,8 +1124,395 @@
         4);
 }
 
-static void ARM64EmitRuntimeFunction(MCStreamer &streamer,
-                                     const WinEH::FrameInfo *info) {
+static uint32_t ARMCountOfUnwindCodes(ArrayRef<WinEH::Instruction> Insns) {
+  uint32_t Count = 0;
+  for (const auto &I : Insns) {
+    switch (static_cast<Win64EH::UnwindOpcodes>(I.Operation)) {
+    default:
+      llvm_unreachable("Unsupported ARM unwind code");
+    case Win64EH::UOP_AllocSmall:
+      Count += 1;
+      break;
+    case Win64EH::UOP_AllocLarge:
+      Count += 3;
+      break;
+    case Win64EH::UOP_AllocHuge:
+      Count += 4;
+      break;
+    case Win64EH::UOP_WideAllocMedium:
+      Count += 2;
+      break;
+    case Win64EH::UOP_WideAllocLarge:
+      Count += 3;
+      break;
+    case Win64EH::UOP_WideAllocHuge:
+      Count += 4;
+      break;
+    case Win64EH::UOP_WideSaveRegMask:
+      Count += 2;
+      break;
+    case Win64EH::UOP_SaveSP:
+      Count += 1;
+      break;
+    case Win64EH::UOP_SaveRegsR4R7LR:
+      Count += 1;
+      break;
+    case Win64EH::UOP_WideSaveRegsR4R11LR:
+      Count += 1;
+      break;
+    case Win64EH::UOP_SaveFRegD8D15:
+      Count += 1;
+      break;
+    case Win64EH::UOP_SaveRegMask:
+      Count += 2;
+      break;
+    case Win64EH::UOP_SaveLR:
+      Count += 2;
+      break;
+    case Win64EH::UOP_SaveFRegD0D15:
+      Count += 2;
+      break;
+    case Win64EH::UOP_SaveFRegD16D31:
+      Count += 2;
+      break;
+    case Win64EH::UOP_Nop:
+    case Win64EH::UOP_WideNop:
+    case Win64EH::UOP_End:
+    case Win64EH::UOP_EndNop:
+    case Win64EH::UOP_WideEndNop:
+      Count += 1;
+      break;
+    case Win64EH::UOP_Custom: {
+      int J;
+      for (J = 3; J > 0; J--)
+        if (I.Offset & (0xffu << (8 * J)))
+          break;
+      Count += J + 1;
+      break;
+    }
+    }
+  }
+  return Count;
+}
+
+// Unwind opcode encodings and restrictions are documented at
+// https://docs.microsoft.com/en-us/cpp/build/arm-exception-handling
+static void ARMEmitUnwindCode(MCStreamer &streamer,
+                              const WinEH::Instruction &inst) {
+  uint32_t w, lr;
+  int i;
+  switch (static_cast<Win64EH::UnwindOpcodes>(inst.Operation)) {
+  default:
+    llvm_unreachable("Unsupported ARM unwind code");
+  case Win64EH::UOP_AllocSmall:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0x7f);
+    streamer.emitInt8(inst.Offset / 4);
+    break;
+  case Win64EH::UOP_WideSaveRegMask:
+    assert((inst.Register & ~0x5fff) == 0);
+    lr = (inst.Register >> 14) & 1;
+    w = 0x8000 | (inst.Register & 0x1fff) | (lr << 13);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_SaveSP:
+    assert(inst.Register <= 0x0f);
+    streamer.emitInt8(0xc0 | inst.Register);
+    break;
+  case Win64EH::UOP_SaveRegsR4R7LR:
+    assert(inst.Register >= 4 && inst.Register <= 7);
+    assert(inst.Offset <= 1);
+    streamer.emitInt8(0xd0 | (inst.Register - 4) | (inst.Offset << 2));
+    break;
+  case Win64EH::UOP_WideSaveRegsR4R11LR:
+    assert(inst.Register >= 8 && inst.Register <= 11);
+    assert(inst.Offset <= 1);
+    streamer.emitInt8(0xd8 | (inst.Register - 8) | (inst.Offset << 2));
+    break;
+  case Win64EH::UOP_SaveFRegD8D15:
+    assert(inst.Register >= 8 && inst.Register <= 15);
+    streamer.emitInt8(0xe0 | (inst.Register - 8));
+    break;
+  case Win64EH::UOP_WideAllocMedium:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0x3ff);
+    w = 0xe800 | (inst.Offset / 4);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_SaveRegMask:
+    assert((inst.Register & ~0x40ff) == 0);
+    lr = (inst.Register >> 14) & 1;
+    w = 0xec00 | (inst.Register & 0x0ff) | (lr << 8);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_SaveLR:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0x0f);
+    streamer.emitInt8(0xef);
+    streamer.emitInt8(inst.Offset / 4);
+    break;
+  case Win64EH::UOP_SaveFRegD0D15:
+    assert(inst.Register <= 15);
+    assert(inst.Offset <= 15);
+    assert(inst.Register <= inst.Offset);
+    streamer.emitInt8(0xf5);
+    streamer.emitInt8((inst.Register << 4) | inst.Offset);
+    break;
+  case Win64EH::UOP_SaveFRegD16D31:
+    assert(inst.Register >= 16 && inst.Register <= 31);
+    assert(inst.Offset >= 16 && inst.Offset <= 31);
+    assert(inst.Register <= inst.Offset);
+    streamer.emitInt8(0xf6);
+    streamer.emitInt8(((inst.Register - 16) << 4) | (inst.Offset - 16));
+    break;
+  case Win64EH::UOP_AllocLarge:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0xffff);
+    w = inst.Offset / 4;
+    streamer.emitInt8(0xf7);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_AllocHuge:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0xffffff);
+    w = inst.Offset / 4;
+    streamer.emitInt8(0xf8);
+    streamer.emitInt8((w >> 16) & 0xff);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_WideAllocLarge:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0xffff);
+    w = inst.Offset / 4;
+    streamer.emitInt8(0xf9);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_WideAllocHuge:
+    assert((inst.Offset & 3) == 0);
+    assert(inst.Offset / 4 <= 0xffffff);
+    w = inst.Offset / 4;
+    streamer.emitInt8(0xfa);
+    streamer.emitInt8((w >> 16) & 0xff);
+    streamer.emitInt8((w >> 8) & 0xff);
+    streamer.emitInt8((w >> 0) & 0xff);
+    break;
+  case Win64EH::UOP_Nop:
+    streamer.emitInt8(0xfb);
+    break;
+  case Win64EH::UOP_WideNop:
+    streamer.emitInt8(0xfc);
+    break;
+  case Win64EH::UOP_EndNop:
+    streamer.emitInt8(0xfd);
+    break;
+  case Win64EH::UOP_WideEndNop:
+    streamer.emitInt8(0xfe);
+    break;
+  case Win64EH::UOP_End:
+    streamer.emitInt8(0xff);
+    break;
+  case Win64EH::UOP_Custom:
+    for (i = 3; i > 0; i--)
+      if (inst.Offset & (0xffu << (8 * i)))
+        break;
+    for (; i >= 0; i--)
+      streamer.emitInt8((inst.Offset >> (8 * i)) & 0xff);
+    break;
+  }
+}
+
+// Populate the .xdata section.  The format of .xdata on ARM is documented at
+// https://docs.microsoft.com/en-us/cpp/build/arm-exception-handling
+static void ARMEmitUnwindInfo(MCStreamer &streamer, WinEH::FrameInfo *info,
+                              bool TryPacked = true) {
+  // If this UNWIND_INFO already has a symbol, it's already been emitted.
+  if (info->Symbol)
+    return;
+  // If there's no unwind info here (not even a terminating UOP_End), the
+  // unwind info is considered bogus and skipped. If this was done in
+  // response to an explicit .seh_handlerdata, the associated trailing
+  // handler data is left orphaned in the xdata section.
+  if (info->empty()) {
+    info->EmitAttempted = true;
+    return;
+  }
+  if (info->EmitAttempted) {
+    // If we tried to emit unwind info before (due to an explicit
+    // .seh_handlerdata directive), but skipped it (because there was no
+    // valid information to emit at the time), and it later got valid unwind
+    // opcodes, we can't emit it here, because the trailing handler data
+    // was already emitted elsewhere in the xdata section.
+    streamer.getContext().reportError(
+        SMLoc(), "Earlier .seh_handlerdata for " + info->Function->getName() +
+                     " skipped due to no unwind info at the time "
+                     "(.seh_handlerdata too early?), but the function later "
+                     "did get unwind info that can't be emitted");
+    return;
+  }
+
+  MCContext &context = streamer.getContext();
+  MCSymbol *Label = context.createTempSymbol();
+
+  streamer.emitValueToAlignment(4);
+  streamer.emitLabel(Label);
+  info->Symbol = Label;
+
+  Optional<int64_t> RawFuncLength;
+  const MCExpr *FuncLengthExpr = nullptr;
+  if (!info->FuncletOrFuncEnd) {
+    report_fatal_error("FuncletOrFuncEnd not set");
+  } else {
+    // As the size of many thumb2 instructions isn't known until later,
+    // we can't always rely on being able to calculate the absolute
+    // length of the function here. If we can't calculate it, defer it
+    // to a relocation.
+    //
+    // In such a case, we won't know if the function is too long so that
+    // the unwind info would need to be split (but this isn't implemented
+    // anyway).
+    RawFuncLength =
+        GetOptionalAbsDifference(streamer, info->FuncletOrFuncEnd, info->Begin);
+    if (!RawFuncLength)
+      FuncLengthExpr =
+          GetSubDivExpr(streamer, info->FuncletOrFuncEnd, info->Begin, 2);
+  }
+  uint32_t FuncLength = 0;
+  if (RawFuncLength)
+    FuncLength = (uint32_t)*RawFuncLength / 2;
+  if (FuncLength > 0x3FFFF)
+    report_fatal_error("SEH unwind data splitting not yet implemented");
+  uint32_t PrologCodeBytes = ARMCountOfUnwindCodes(info->Instructions);
+  uint32_t TotalCodeBytes = PrologCodeBytes;
+
+  // Process epilogs.
+  MapVector<MCSymbol *, uint32_t> EpilogInfo;
+  // Epilogs processed so far.
+  std::vector<MCSymbol *> AddedEpilogs;
+
+  for (auto &I : info->EpilogMap) {
+    MCSymbol *EpilogStart = I.first;
+    auto &EpilogInstrs = I.second.Instructions;
+    uint32_t CodeBytes = ARMCountOfUnwindCodes(EpilogInstrs);
+
+    MCSymbol *MatchingEpilog =
+        FindMatchingEpilog(EpilogInstrs, AddedEpilogs, info);
+    if (MatchingEpilog) {
+      assert(EpilogInfo.find(MatchingEpilog) != EpilogInfo.end() &&
+             "Duplicate epilog not found");
+      EpilogInfo[EpilogStart] = EpilogInfo.lookup(MatchingEpilog);
+      // Clear the unwind codes in the EpilogMap, so that they don't get output
+      // in the logic below.
+      EpilogInstrs.clear();
+    } else {
+      EpilogInfo[EpilogStart] = TotalCodeBytes;
+      TotalCodeBytes += CodeBytes;
+      AddedEpilogs.push_back(EpilogStart);
+    }
+  }
+
+  // Code Words, Epilog count, F, E, X, Vers, Function Length
+  uint32_t row1 = 0x0;
+  uint32_t CodeWords = TotalCodeBytes / 4;
+  uint32_t CodeWordsMod = TotalCodeBytes % 4;
+  if (CodeWordsMod)
+    CodeWords++;
+  uint32_t EpilogCount = info->EpilogMap.size();
+  bool ExtensionWord = EpilogCount > 31 || CodeWords > 15;
+  if (!ExtensionWord) {
+    row1 |= (EpilogCount & 0x1F) << 23;
+    row1 |= (CodeWords & 0x0F) << 28;
+  }
+  if (info->HandlesExceptions) // X
+    row1 |= 1 << 20;
+  if (info->Fragment) // F
+    row1 |= 1 << 22;
+  row1 |= FuncLength & 0x3FFFF;
+  if (RawFuncLength)
+    streamer.emitInt32(row1);
+  else
+    streamer.emitValue(
+        MCBinaryExpr::createOr(FuncLengthExpr,
+                               MCConstantExpr::create(row1, context), context),
+        4);
+
+  // Extended Code Words, Extended Epilog Count
+  if (ExtensionWord) {
+    // FIXME: We should be able to split unwind info into multiple sections.
+    if (CodeWords > 0xFF || EpilogCount > 0xFFFF)
+      report_fatal_error("SEH unwind data splitting not yet implemented");
+    uint32_t row2 = 0x0;
+    row2 |= (CodeWords & 0xFF) << 16;
+    row2 |= (EpilogCount & 0xFFFF);
+    streamer.emitInt32(row2);
+  }
+
+  // Epilog Start Index, Epilog Start Offset
+  for (auto &I : EpilogInfo) {
+    MCSymbol *EpilogStart = I.first;
+    uint32_t EpilogIndex = I.second;
+
+    Optional<int64_t> MaybeEpilogOffset =
+        GetOptionalAbsDifference(streamer, EpilogStart, info->Begin);
+    const MCExpr *OffsetExpr = nullptr;
+    uint32_t EpilogOffset = 0;
+    if (MaybeEpilogOffset)
+      EpilogOffset = *MaybeEpilogOffset / 2;
+    else
+      OffsetExpr = GetSubDivExpr(streamer, EpilogStart, info->Begin, 2);
+
+    assert(info->EpilogMap.find(EpilogStart) != info->EpilogMap.end());
+    unsigned Condition = info->EpilogMap[EpilogStart].Condition;
+    assert(Condition <= 0xf);
+
+    uint32_t row3 = EpilogOffset;
+    row3 |= Condition << 20;
+    row3 |= (EpilogIndex & 0x3FF) << 24;
+    if (MaybeEpilogOffset)
+      streamer.emitInt32(row3);
+    else
+      streamer.emitValue(
+          MCBinaryExpr::createOr(
+              OffsetExpr, MCConstantExpr::create(row3, context), context),
+          4);
+  }
+
+  // Emit prolog unwind instructions (in reverse order).
+  uint8_t numInst = info->Instructions.size();
+  for (uint8_t c = 0; c < numInst; ++c) {
+    WinEH::Instruction inst = info->Instructions.back();
+    info->Instructions.pop_back();
+    ARMEmitUnwindCode(streamer, inst);
+  }
+
+  // Emit epilog unwind instructions
+  for (auto &I : info->EpilogMap) {
+    auto &EpilogInstrs = I.second.Instructions;
+    for (uint32_t i = 0; i < EpilogInstrs.size(); i++) {
+      WinEH::Instruction inst = EpilogInstrs[i];
+      ARMEmitUnwindCode(streamer, inst);
+    }
+  }
+
+  int32_t BytesMod = CodeWords * 4 - TotalCodeBytes;
+  assert(BytesMod >= 0);
+  for (int i = 0; i < BytesMod; i++)
+    streamer.emitInt8(0xFB);
+
+  if (info->HandlesExceptions)
+    streamer.emitValue(
+        MCSymbolRefExpr::create(info->ExceptionHandler,
+                                MCSymbolRefExpr::VK_COFF_IMGREL32, context),
+        4);
+}
+
+static void ARMEmitRuntimeFunction(MCStreamer &streamer,
+                                   const WinEH::FrameInfo *info) {
   MCContext &context = streamer.getContext();
 
   streamer.emitValueToAlignment(4);
@@ -1138,7 +1547,7 @@
       continue;
     MCSection *PData = Streamer.getAssociatedPDataSection(CFI->TextSection);
     Streamer.SwitchSection(PData);
-    ARM64EmitRuntimeFunction(Streamer, Info);
+    ARMEmitRuntimeFunction(Streamer, Info);
   }
 }
 
@@ -1161,3 +1570,48 @@
   Streamer.SwitchSection(XData);
   ARM64EmitUnwindInfo(Streamer, info, /* TryPacked = */ !HandlerData);
 }
+
+void llvm::Win64EH::ARMUnwindEmitter::Emit(MCStreamer &Streamer) const {
+  // Emit the unwind info structs first.
+  for (const auto &CFI : Streamer.getWinFrameInfos()) {
+    WinEH::FrameInfo *Info = CFI.get();
+    if (Info->empty())
+      continue;
+    MCSection *XData = Streamer.getAssociatedXDataSection(CFI->TextSection);
+    Streamer.SwitchSection(XData);
+    ARMEmitUnwindInfo(Streamer, Info);
+  }
+
+  // Now emit RUNTIME_FUNCTION entries.
+  for (const auto &CFI : Streamer.getWinFrameInfos()) {
+    WinEH::FrameInfo *Info = CFI.get();
+    // ARMEmitUnwindInfo above clears the info struct, so we can't check
+    // empty here. But if a Symbol is set, we should create the corresponding
+    // pdata entry.
+    if (!Info->Symbol)
+      continue;
+    MCSection *PData = Streamer.getAssociatedPDataSection(CFI->TextSection);
+    Streamer.SwitchSection(PData);
+    ARMEmitRuntimeFunction(Streamer, Info);
+  }
+}
+
+void llvm::Win64EH::ARMUnwindEmitter::EmitUnwindInfo(MCStreamer &Streamer,
+                                                     WinEH::FrameInfo *info,
+                                                     bool HandlerData) const {
+  // Called if there's an .seh_handlerdata directive before the end of the
+  // function. This forces writing the xdata record already here - and
+  // in this case, the function isn't actually ended already, but the xdata
+  // record needs to know the function length. In these cases, if the funclet
+  // end hasn't been marked yet, the xdata function length won't cover the
+  // whole function, only up to this point.
+  if (!info->FuncletOrFuncEnd) {
+    Streamer.SwitchSection(info->TextSection);
+    info->FuncletOrFuncEnd = Streamer.emitCFILabel();
+  }
+  // Switch sections (the static function above is meant to be called from
+  // here and from Emit().
+  MCSection *XData = Streamer.getAssociatedXDataSection(info->TextSection);
+  Streamer.SwitchSection(XData);
+  ARMEmitUnwindInfo(Streamer, info, /* TryPacked = */ !HandlerData);
+}
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -453,6 +453,7 @@
                          bool AllowRAAC = false);
   bool parseMemory(OperandVector &);
   bool parseOperand(OperandVector &, StringRef Mnemonic);
+  bool parseImmExpr(int64_t &Out);
   bool parsePrefix(ARMMCExpr::VariantKind &RefKind);
   bool parseMemRegOffsetShift(ARM_AM::ShiftOpc &ShiftType,
                               unsigned &ShiftAmount);
@@ -488,6 +489,17 @@
   bool parseDirectiveAlign(SMLoc L);
   bool parseDirectiveThumbSet(SMLoc L);
 
+  bool parseDirectiveSEHAllocStack(SMLoc L, bool Wide);
+  bool parseDirectiveSEHSaveRegs(SMLoc L, bool Wide);
+  bool parseDirectiveSEHSaveSP(SMLoc L);
+  bool parseDirectiveSEHSaveFRegs(SMLoc L);
+  bool parseDirectiveSEHSaveLR(SMLoc L);
+  bool parseDirectiveSEHPrologEnd(SMLoc L, bool Fragment);
+  bool parseDirectiveSEHNop(SMLoc L, bool Wide);
+  bool parseDirectiveSEHEpilogStart(SMLoc L, bool Condition);
+  bool parseDirectiveSEHEpilogEnd(SMLoc L);
+  bool parseDirectiveSEHCustom(SMLoc L);
+
   bool isMnemonicVPTPredicable(StringRef Mnemonic, StringRef ExtraToken);
   StringRef splitMnemonic(StringRef Mnemonic, StringRef ExtraToken,
                           unsigned &PredicationCode,
@@ -6317,6 +6329,18 @@
   }
 }
 
+bool ARMAsmParser::parseImmExpr(int64_t &Out) {
+  const MCExpr *Expr = nullptr;
+  SMLoc L = getParser().getTok().getLoc();
+  if (check(getParser().parseExpression(Expr), L, "expected expression"))
+    return true;
+  const MCConstantExpr *Value = dyn_cast_or_null<MCConstantExpr>(Expr);
+  if (check(!Value, L, "expected constant expression"))
+    return true;
+  Out = Value->getValue();
+  return false;
+}
+
 // parsePrefix - Parse ARM 16-bit relocations expression prefix, i.e.
 //  :lower16: and :upper16:.
 bool ARMAsmParser::parsePrefix(ARMMCExpr::VariantKind &RefKind) {
@@ -11082,6 +11106,39 @@
       parseDirectiveTLSDescSeq(DirectiveID.getLoc());
     else
       return true;
+  } else if (IsCOFF) {
+    if (IDVal == ".seh_stackalloc")
+      parseDirectiveSEHAllocStack(DirectiveID.getLoc(), /*Wide=*/false);
+    else if (IDVal == ".seh_stackalloc_w")
+      parseDirectiveSEHAllocStack(DirectiveID.getLoc(), /*Wide=*/true);
+    else if (IDVal == ".seh_save_regs")
+      parseDirectiveSEHSaveRegs(DirectiveID.getLoc(), /*Wide=*/false);
+    else if (IDVal == ".seh_save_regs_w")
+      parseDirectiveSEHSaveRegs(DirectiveID.getLoc(), /*Wide=*/true);
+    else if (IDVal == ".seh_save_sp")
+      parseDirectiveSEHSaveSP(DirectiveID.getLoc());
+    else if (IDVal == ".seh_save_fregs")
+      parseDirectiveSEHSaveFRegs(DirectiveID.getLoc());
+    else if (IDVal == ".seh_save_lr")
+      parseDirectiveSEHSaveLR(DirectiveID.getLoc());
+    else if (IDVal == ".seh_endprologue")
+      parseDirectiveSEHPrologEnd(DirectiveID.getLoc(), /*Fragment=*/false);
+    else if (IDVal == ".seh_endprologue_fragment")
+      parseDirectiveSEHPrologEnd(DirectiveID.getLoc(), /*Fragment=*/true);
+    else if (IDVal == ".seh_nop")
+      parseDirectiveSEHNop(DirectiveID.getLoc(), /*Wide=*/false);
+    else if (IDVal == ".seh_nop_w")
+      parseDirectiveSEHNop(DirectiveID.getLoc(), /*Wide=*/true);
+    else if (IDVal == ".seh_startepilogue")
+      parseDirectiveSEHEpilogStart(DirectiveID.getLoc(), /*Condition=*/false);
+    else if (IDVal == ".seh_startepilogue_cond")
+      parseDirectiveSEHEpilogStart(DirectiveID.getLoc(), /*Condition=*/true);
+    else if (IDVal == ".seh_endepilogue")
+      parseDirectiveSEHEpilogEnd(DirectiveID.getLoc());
+    else if (IDVal == ".seh_custom")
+      parseDirectiveSEHCustom(DirectiveID.getLoc());
+    else
+      return true;
   } else
     return true;
   return false;
@@ -12018,6 +12075,177 @@
   return false;
 }
 
+/// parseDirectiveSEHAllocStack
+/// ::= .seh_stackalloc
+/// ::= .seh_stackalloc_w
+bool ARMAsmParser::parseDirectiveSEHAllocStack(SMLoc L, bool Wide) {
+  int64_t Size;
+  if (parseImmExpr(Size))
+    return true;
+  getTargetStreamer().emitARMWinCFIAllocStack(Size, Wide);
+  return false;
+}
+
+/// parseDirectiveSEHSaveRegs
+/// ::= .seh_save_regs
+/// ::= .seh_save_regs_w
+bool ARMAsmParser::parseDirectiveSEHSaveRegs(SMLoc L, bool Wide) {
+  SmallVector<std::unique_ptr<MCParsedAsmOperand>, 1> Operands;
+
+  if (parseRegisterList(Operands) ||
+      parseToken(AsmToken::EndOfStatement, "unexpected token in directive"))
+    return true;
+  ARMOperand &Op = (ARMOperand &)*Operands[0];
+  if (!Op.isRegList())
+    return Error(L, ".seh_save_regs{_w} expects GPR registers");
+  const SmallVectorImpl<unsigned> &RegList = Op.getRegList();
+  uint32_t Mask = 0;
+  for (size_t i = 0; i < RegList.size(); ++i) {
+    unsigned Reg = MRI->getEncodingValue(RegList[i]);
+    if (Reg == 15) // pc -> lr
+      Reg = 14;
+    if (Reg == 13)
+      return Error(L, ".seh_save_regs{_w} can't include SP");
+    assert(Reg < 16U && "Register out of range");
+    unsigned Bit = (1u << Reg);
+    Mask |= Bit;
+  }
+  if (!Wide && (Mask & 0x1f00) != 0)
+    return Error(L,
+                 ".seh_save_regs cannot save R8-R12, needs .seh_save_regs_w");
+  getTargetStreamer().emitARMWinCFISaveRegMask(Mask, Wide);
+  return false;
+}
+
+/// parseDirectiveSEHSaveSP
+/// ::= .seh_save_sp
+bool ARMAsmParser::parseDirectiveSEHSaveSP(SMLoc L) {
+  int Reg = tryParseRegister();
+  if (Reg == -1 || !MRI->getRegClass(ARM::GPRRegClassID).contains(Reg))
+    return Error(L, "expected GPR");
+  unsigned Index = MRI->getEncodingValue(Reg);
+  if (Index > 14 || Index == 13)
+    return Error(L, "invalid register for .seh_save_sp");
+  getTargetStreamer().emitARMWinCFISaveSP(Index);
+  return false;
+}
+
+/// parseDirectiveSEHSaveFRegs
+/// ::= .seh_save_fregs
+bool ARMAsmParser::parseDirectiveSEHSaveFRegs(SMLoc L) {
+  SmallVector<std::unique_ptr<MCParsedAsmOperand>, 1> Operands;
+
+  if (parseRegisterList(Operands) ||
+      parseToken(AsmToken::EndOfStatement, "unexpected token in directive"))
+    return true;
+  ARMOperand &Op = (ARMOperand &)*Operands[0];
+  if (!Op.isDPRRegList())
+    return Error(L, ".seh_save_fregs expects DPR registers");
+  const SmallVectorImpl<unsigned> &RegList = Op.getRegList();
+  uint32_t Mask = 0;
+  for (size_t i = 0; i < RegList.size(); ++i) {
+    unsigned Reg = MRI->getEncodingValue(RegList[i]);
+    assert(Reg < 32U && "Register out of range");
+    unsigned Bit = (1u << Reg);
+    Mask |= Bit;
+  }
+
+  if (Mask == 0)
+    return Error(L, ".seh_save_fregs missing registers");
+
+  unsigned First = 0;
+  while ((Mask & 1) == 0) {
+    First++;
+    Mask >>= 1;
+  }
+  if (((Mask + 1) & Mask) != 0)
+    return Error(L,
+                 ".seh_save_fregs must take a contiguous range of registers");
+  unsigned Last = First;
+  while ((Mask & 2) != 0) {
+    Last++;
+    Mask >>= 1;
+  }
+  if (First < 16 && Last >= 16)
+    return Error(L, ".seh_save_fregs must be all d0-d15 or d16-d31");
+  getTargetStreamer().emitARMWinCFISaveFRegs(First, Last);
+  return false;
+}
+
+/// parseDirectiveSEHSaveLR
+/// ::= .seh_save_lr
+bool ARMAsmParser::parseDirectiveSEHSaveLR(SMLoc L) {
+  int64_t Offset;
+  if (parseImmExpr(Offset))
+    return true;
+  getTargetStreamer().emitARMWinCFISaveLR(Offset);
+  return false;
+}
+
+/// parseDirectiveSEHPrologEnd
+/// ::= .seh_endprologue
+/// ::= .seh_endprologue_fragment
+bool ARMAsmParser::parseDirectiveSEHPrologEnd(SMLoc L, bool Fragment) {
+  getTargetStreamer().emitARMWinCFIPrologEnd(Fragment);
+  return false;
+}
+
+/// parseDirectiveSEHNop
+/// ::= .seh_nop
+/// ::= .seh_nop_w
+bool ARMAsmParser::parseDirectiveSEHNop(SMLoc L, bool Wide) {
+  getTargetStreamer().emitARMWinCFINop(Wide);
+  return false;
+}
+
+/// parseDirectiveSEHEpilogStart
+/// ::= .seh_startepilogue
+/// ::= .seh_startepilogue_cond
+bool ARMAsmParser::parseDirectiveSEHEpilogStart(SMLoc L, bool Condition) {
+  unsigned CC = ARMCC::AL;
+  if (Condition) {
+    MCAsmParser &Parser = getParser();
+    SMLoc S = Parser.getTok().getLoc();
+    const AsmToken &Tok = Parser.getTok();
+    if (!Tok.is(AsmToken::Identifier))
+      return Error(S, ".seh_startepilogue_cond missing condition");
+    CC = ARMCondCodeFromString(Tok.getString());
+    if (CC == ~0U)
+      return Error(S, "invalid condition");
+    Parser.Lex(); // Eat the token.
+  }
+
+  getTargetStreamer().emitARMWinCFIEpilogStart(CC);
+  return false;
+}
+
+/// parseDirectiveSEHEpilogEnd
+/// ::= .seh_endepilogue
+bool ARMAsmParser::parseDirectiveSEHEpilogEnd(SMLoc L) {
+  getTargetStreamer().emitARMWinCFIEpilogEnd();
+  return false;
+}
+
+/// parseDirectiveSEHCustom
+/// ::= .seh_custom
+bool ARMAsmParser::parseDirectiveSEHCustom(SMLoc L) {
+  unsigned Opcode = 0;
+  do {
+    int64_t Byte;
+    if (parseImmExpr(Byte))
+      return true;
+    if (Byte > 0xff || Byte < 0)
+      return Error(L, "Invalid byte value in .seh_custom");
+    if (Opcode > 0x00ffffff)
+      return Error(L, "Too many bytes in .seh_custom");
+    // Store the bytes as one big endian number in Opcode. In a multi byte
+    // opcode sequence, the first byte can't be zero.
+    Opcode = (Opcode << 8) | Byte;
+  } while (parseOptionalToken(AsmToken::Comma));
+  getTargetStreamer().emitARMWinCFICustom(Opcode);
+  return false;
+}
+
 /// Force static initialization.
 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeARMAsmParser() {
   RegisterMCAsmParser<ARMAsmParser> X(getTheARMLETarget());
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -101,6 +101,17 @@
   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
 
+  void emitARMWinCFIAllocStack(unsigned Size, bool Wide) override;
+  void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) override;
+  void emitARMWinCFISaveSP(unsigned Reg) override;
+  void emitARMWinCFISaveFRegs(unsigned First, unsigned Last) override;
+  void emitARMWinCFISaveLR(unsigned Offset) override;
+  void emitARMWinCFIPrologEnd(bool Fragment) override;
+  void emitARMWinCFINop(bool Wide) override;
+  void emitARMWinCFIEpilogStart(unsigned Condition) override;
+  void emitARMWinCFIEpilogEnd() override;
+  void emitARMWinCFICustom(unsigned Opcode) override;
+
 public:
   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
                        MCInstPrinter &InstPrinter, bool VerboseAsm);
@@ -269,6 +280,101 @@
   OS << '\n';
 }
 
+void ARMTargetAsmStreamer::emitARMWinCFIAllocStack(unsigned Size, bool Wide) {
+  if (Wide)
+    OS << "\t.seh_stackalloc_w\t" << Size << "\n";
+  else
+    OS << "\t.seh_stackalloc\t" << Size << "\n";
+}
+
+static void printRegs(formatted_raw_ostream &OS, ListSeparator &LS, int First,
+                      int Last) {
+  if (First != Last)
+    OS << LS << "r" << First << "-r" << Last;
+  else
+    OS << LS << "r" << First;
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) {
+  if (Wide)
+    OS << "\t.seh_save_regs_w\t";
+  else
+    OS << "\t.seh_save_regs\t";
+  ListSeparator LS;
+  int First = -1;
+  OS << "{";
+  for (int I = 0; I <= 12; I++) {
+    if (Mask & (1 << I)) {
+      if (First < 0)
+        First = I;
+    } else {
+      if (First >= 0) {
+        printRegs(OS, LS, First, I - 1);
+        First = -1;
+      }
+    }
+  }
+  if (First >= 0)
+    printRegs(OS, LS, First, 12);
+  if (Mask & (1 << 14))
+    OS << LS << "lr";
+  OS << "}\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFISaveSP(unsigned Reg) {
+  OS << "\t.seh_save_sp\tr" << Reg << "\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFISaveFRegs(unsigned First,
+                                                  unsigned Last) {
+  if (First != Last)
+    OS << "\t.seh_save_fregs\t{d" << First << "-d" << Last << "}\n";
+  else
+    OS << "\t.seh_save_fregs\t{d" << First << "}\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFISaveLR(unsigned Offset) {
+  OS << "\t.seh_save_lr\t" << Offset << "\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFIPrologEnd(bool Fragment) {
+  if (Fragment)
+    OS << "\t.seh_endprologue_fragment\n";
+  else
+    OS << "\t.seh_endprologue\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFINop(bool Wide) {
+  if (Wide)
+    OS << "\t.seh_nop_w\n";
+  else
+    OS << "\t.seh_nop\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFIEpilogStart(unsigned Condition) {
+  if (Condition == ARMCC::AL)
+    OS << "\t.seh_startepilogue\n";
+  else
+    OS << "\t.seh_startepilogue_cond\t"
+       << ARMCondCodeToString(static_cast<ARMCC::CondCodes>(Condition)) << "\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFIEpilogEnd() {
+  OS << "\t.seh_endepilogue\n";
+}
+
+void ARMTargetAsmStreamer::emitARMWinCFICustom(unsigned Opcode) {
+  int I;
+  for (I = 3; I > 0; I--)
+    if (Opcode & (0xffu << (8 * I)))
+      break;
+  ListSeparator LS;
+  OS << "\t.seh_custom\t";
+  for (; I >= 0; I--)
+    OS << LS << ((Opcode >> (8 * I)) & 0xff);
+  OS << "\n";
+}
+
 class ARMTargetELFStreamer : public ARMTargetStreamer {
 private:
   StringRef CurrentVendor;
@@ -1369,12 +1475,8 @@
   return new ARMTargetStreamer(S);
 }
 
-MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
-                                                const MCSubtargetInfo &STI) {
-  const Triple &TT = STI.getTargetTriple();
-  if (TT.isOSBinFormatELF())
-    return new ARMTargetELFStreamer(S);
-  return new ARMTargetStreamer(S);
+MCTargetStreamer *createARMObjectTargetELFStreamer(MCStreamer &S) {
+  return new ARMTargetELFStreamer(S);
 }
 
 MCELFStreamer *createARMELFStreamer(MCContext &Context,
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp
@@ -89,6 +89,7 @@
   AlignmentIsInBytes = false;
   SupportsDebugInformation = true;
   ExceptionsType = ExceptionHandling::WinEH;
+  WinEHEncodingType = WinEH::EncodingType::Itanium;
   PrivateGlobalPrefix = "$M";
   PrivateLabelPrefix = "$M";
   CommentString = "@";
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
@@ -71,6 +71,8 @@
                                              bool isVerboseAsm);
 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
                                                 const MCSubtargetInfo &STI);
+MCTargetStreamer *createARMObjectTargetELFStreamer(MCStreamer &S);
+MCTargetStreamer *createARMObjectTargetWinCOFFStreamer(MCStreamer &S);
 
 MCCodeEmitter *createARMLEMCCodeEmitter(const MCInstrInfo &MCII,
                                         MCContext &Ctx);
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
@@ -118,6 +118,17 @@
 ARMTargetStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) {}
 void ARMTargetStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {}
 
+void ARMTargetStreamer::emitARMWinCFIAllocStack(unsigned Size, bool Wide) {}
+void ARMTargetStreamer::emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) {}
+void ARMTargetStreamer::emitARMWinCFISaveSP(unsigned Reg) {}
+void ARMTargetStreamer::emitARMWinCFISaveFRegs(unsigned First, unsigned Last) {}
+void ARMTargetStreamer::emitARMWinCFISaveLR(unsigned Offset) {}
+void ARMTargetStreamer::emitARMWinCFINop(bool Wide) {}
+void ARMTargetStreamer::emitARMWinCFIPrologEnd(bool Fragment) {}
+void ARMTargetStreamer::emitARMWinCFIEpilogStart(unsigned Condition) {}
+void ARMTargetStreamer::emitARMWinCFIEpilogEnd() {}
+void ARMTargetStreamer::emitARMWinCFICustom(unsigned Opcode) {}
+
 static ARMBuildAttrs::CPUArch getArchForCPU(const MCSubtargetInfo &STI) {
   if (STI.getCPU() == "xscale")
     return ARMBuildAttrs::v5TEJ;
@@ -307,3 +318,13 @@
     emitAttribute(ARMBuildAttrs::BTI_extension, ARMBuildAttrs::AllowBTI);
   }
 }
+
+MCTargetStreamer *
+llvm::createARMObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
+  const Triple &TT = STI.getTargetTriple();
+  if (TT.isOSBinFormatELF())
+    return createARMObjectTargetELFStreamer(S);
+  if (TT.isOSBinFormatCOFF())
+    return createARMObjectTargetWinCOFFStreamer(S);
+  return new ARMTargetStreamer(S);
+}
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
@@ -7,32 +7,60 @@
 //===----------------------------------------------------------------------===//
 
 #include "ARMMCTargetDesc.h"
+#include "Utils/ARMBaseInfo.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCWin64EH.h"
 #include "llvm/MC/MCWinCOFFStreamer.h"
 
 using namespace llvm;
 
 namespace {
 class ARMWinCOFFStreamer : public MCWinCOFFStreamer {
+  Win64EH::ARMUnwindEmitter EHStreamer;
+
 public:
   ARMWinCOFFStreamer(MCContext &C, std::unique_ptr<MCAsmBackend> AB,
                      std::unique_ptr<MCCodeEmitter> CE,
                      std::unique_ptr<MCObjectWriter> OW)
       : MCWinCOFFStreamer(C, std::move(AB), std::move(CE), std::move(OW)) {}
 
+  void EmitWinEHHandlerData(SMLoc Loc) override;
+  void EmitWindowsUnwindTables() override;
+  void EmitWindowsUnwindTables(WinEH::FrameInfo *Frame) override;
+
   void emitThumbFunc(MCSymbol *Symbol) override;
   void finishImpl() override;
 };
 
+void ARMWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
+  MCStreamer::EmitWinEHHandlerData(Loc);
+
+  // We have to emit the unwind info now, because this directive
+  // actually switches to the .xdata section!
+  EHStreamer.EmitUnwindInfo(*this, getCurrentWinFrameInfo(),
+                            /* HandlerData = */ true);
+}
+
+void ARMWinCOFFStreamer::EmitWindowsUnwindTables(WinEH::FrameInfo *Frame) {
+  EHStreamer.EmitUnwindInfo(*this, Frame, /* HandlerData = */ false);
+}
+
+void ARMWinCOFFStreamer::EmitWindowsUnwindTables() {
+  if (!getNumWinFrameInfos())
+    return;
+  EHStreamer.Emit(*this);
+}
+
 void ARMWinCOFFStreamer::emitThumbFunc(MCSymbol *Symbol) {
   getAssembler().setIsThumbFunc(Symbol);
 }
 
 void ARMWinCOFFStreamer::finishImpl() {
   emitFrames(nullptr);
+  EmitWindowsUnwindTables();
 
   MCWinCOFFStreamer::finishImpl();
 }
@@ -49,3 +77,193 @@
   return S;
 }
 
+namespace {
+class ARMTargetWinCOFFStreamer : public llvm::ARMTargetStreamer {
+private:
+  // True if we are processing SEH directives in an epilogue.
+  bool InEpilogCFI = false;
+
+  // Symbol of the current epilog for which we are processing SEH directives.
+  MCSymbol *CurrentEpilog = nullptr;
+
+public:
+  ARMTargetWinCOFFStreamer(llvm::MCStreamer &S) : ARMTargetStreamer(S) {}
+
+  // The unwind codes on ARM Windows are documented at
+  // https://docs.microsoft.com/en-us/cpp/build/arm-exception-handling
+  void emitARMWinCFIAllocStack(unsigned Size, bool Wide) override;
+  void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) override;
+  void emitARMWinCFISaveSP(unsigned Reg) override;
+  void emitARMWinCFISaveFRegs(unsigned First, unsigned Last) override;
+  void emitARMWinCFISaveLR(unsigned Offset) override;
+  void emitARMWinCFIPrologEnd(bool Fragment) override;
+  void emitARMWinCFINop(bool Wide) override;
+  void emitARMWinCFIEpilogStart(unsigned Condition) override;
+  void emitARMWinCFIEpilogEnd() override;
+  void emitARMWinCFICustom(unsigned Opcode) override;
+
+private:
+  void emitARMWinUnwindCode(unsigned UnwindCode, int Reg, int Offset);
+};
+
+// Helper function to common out unwind code setup for those codes that can
+// belong to both prolog and epilog.
+void ARMTargetWinCOFFStreamer::emitARMWinUnwindCode(unsigned UnwindCode,
+                                                    int Reg, int Offset) {
+  auto &S = getStreamer();
+  WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
+  if (!CurFrame)
+    return;
+  MCSymbol *Label = S.emitCFILabel();
+  auto Inst = WinEH::Instruction(UnwindCode, Label, Reg, Offset);
+  if (InEpilogCFI)
+    CurFrame->EpilogMap[CurrentEpilog].Instructions.push_back(Inst);
+  else
+    CurFrame->Instructions.push_back(Inst);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFIAllocStack(unsigned Size,
+                                                       bool Wide) {
+  unsigned Op = Win64EH::UOP_AllocSmall;
+  if (!Wide) {
+    if (Size / 4 > 0xffff)
+      Op = Win64EH::UOP_AllocHuge;
+    else if (Size / 4 > 0x7f)
+      Op = Win64EH::UOP_AllocLarge;
+  } else {
+    Op = Win64EH::UOP_WideAllocMedium;
+    if (Size / 4 > 0xffff)
+      Op = Win64EH::UOP_WideAllocHuge;
+    else if (Size / 4 > 0x3ff)
+      Op = Win64EH::UOP_WideAllocLarge;
+  }
+  emitARMWinUnwindCode(Op, -1, Size);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFISaveRegMask(unsigned Mask,
+                                                        bool Wide) {
+  assert(Mask != 0);
+  int Lr = (Mask & 0x4000) ? 1 : 0;
+  Mask &= ~0x4000;
+  if (Wide)
+    assert((Mask & ~0x1fff) == 0);
+  else
+    assert((Mask & ~0x00ff) == 0);
+  if (Mask && ((Mask + (1 << 4)) & Mask) == 0) {
+    if (Wide && (Mask & 0x1000) == 0 && (Mask & 0xff) == 0xf0) {
+      // One continuous range from r4 to r8-r11
+      for (int I = 11; I >= 8; I--) {
+        if (Mask & (1 << I)) {
+          emitARMWinUnwindCode(Win64EH::UOP_WideSaveRegsR4R11LR, I, Lr);
+          return;
+        }
+      }
+      // If it actually was from r4 to r4-r7, continue below.
+    } else if (!Wide) {
+      // One continuous range from r4 to r4-r7
+      for (int I = 7; I >= 4; I--) {
+        if (Mask & (1 << I)) {
+          emitARMWinUnwindCode(Win64EH::UOP_SaveRegsR4R7LR, I, Lr);
+          return;
+        }
+      }
+      llvm_unreachable("logic error");
+    }
+  }
+  Mask |= Lr << 14;
+  if (Wide)
+    emitARMWinUnwindCode(Win64EH::UOP_WideSaveRegMask, Mask, 0);
+  else
+    emitARMWinUnwindCode(Win64EH::UOP_SaveRegMask, Mask, 0);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFISaveSP(unsigned Reg) {
+  emitARMWinUnwindCode(Win64EH::UOP_SaveSP, Reg, 0);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFISaveFRegs(unsigned First,
+                                                      unsigned Last) {
+  assert(First <= Last);
+  assert(First >= 16 || Last < 16);
+  assert(First <= 31 && Last <= 31);
+  if (First == 8)
+    emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD8D15, Last, 0);
+  else if (First <= 15)
+    emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD0D15, First, Last);
+  else
+    emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD16D31, First, Last);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFISaveLR(unsigned Offset) {
+  emitARMWinUnwindCode(Win64EH::UOP_SaveLR, 0, Offset);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFINop(bool Wide) {
+  if (Wide)
+    emitARMWinUnwindCode(Win64EH::UOP_WideNop, -1, 0);
+  else
+    emitARMWinUnwindCode(Win64EH::UOP_Nop, -1, 0);
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFIPrologEnd(bool Fragment) {
+  auto &S = getStreamer();
+  WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
+  if (!CurFrame)
+    return;
+
+  MCSymbol *Label = S.emitCFILabel();
+  CurFrame->PrologEnd = Label;
+  WinEH::Instruction Inst =
+      WinEH::Instruction(Win64EH::UOP_End, /*Label=*/nullptr, -1, 0);
+  auto it = CurFrame->Instructions.begin();
+  CurFrame->Instructions.insert(it, Inst);
+  CurFrame->Fragment = Fragment;
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFIEpilogStart(unsigned Condition) {
+  auto &S = getStreamer();
+  WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
+  if (!CurFrame)
+    return;
+
+  InEpilogCFI = true;
+  CurrentEpilog = S.emitCFILabel();
+  CurFrame->EpilogMap[CurrentEpilog].Condition = Condition;
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFIEpilogEnd() {
+  auto &S = getStreamer();
+  WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
+  if (!CurFrame)
+    return;
+
+  std::vector<WinEH::Instruction> &Epilog =
+      CurFrame->EpilogMap[CurrentEpilog].Instructions;
+
+  unsigned UnwindCode = Win64EH::UOP_End;
+  if (!Epilog.empty()) {
+    WinEH::Instruction EndInstr = Epilog.back();
+    if (EndInstr.Operation == Win64EH::UOP_Nop) {
+      UnwindCode = Win64EH::UOP_EndNop;
+      Epilog.pop_back();
+    } else if (EndInstr.Operation == Win64EH::UOP_WideNop) {
+      UnwindCode = Win64EH::UOP_WideEndNop;
+      Epilog.pop_back();
+    }
+  }
+
+  InEpilogCFI = false;
+  WinEH::Instruction Inst = WinEH::Instruction(UnwindCode, nullptr, -1, 0);
+  CurFrame->EpilogMap[CurrentEpilog].Instructions.push_back(Inst);
+  CurrentEpilog = nullptr;
+}
+
+void ARMTargetWinCOFFStreamer::emitARMWinCFICustom(unsigned Opcode) {
+  emitARMWinUnwindCode(Win64EH::UOP_Custom, 0, Opcode);
+}
+
+} // end anonymous namespace
+
+MCTargetStreamer *llvm::createARMObjectTargetWinCOFFStreamer(MCStreamer &S) {
+  return new ARMTargetWinCOFFStreamer(S);
+}
diff --git a/llvm/test/MC/ARM/seh.s b/llvm/test/MC/ARM/seh.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/ARM/seh.s
@@ -0,0 +1,347 @@
+// This test checks that the SEH directives emit the correct unwind data.
+
+// RUN: llvm-mc -triple thumbv7-pc-win32 -filetype=obj %s | llvm-readobj -S -r -u - | FileCheck %s
+
+// Check that the output assembler directives also can be parsed, and
+// that they produce equivalent output:
+
+// RUN: llvm-mc -triple thumbv7-pc-win32 -filetype=asm %s | llvm-mc -triple thumbv7-pc-win32 -filetype=obj - | llvm-readobj -S -r -u - | FileCheck %s
+
+// CHECK:      Sections [
+// CHECK:        Section {
+// CHECK:          Name: .text
+// CHECK:          RelocationCount: 1
+// CHECK:          Characteristics [
+// CHECK-NEXT:       ALIGN_4BYTES
+// CHECK-NEXT:       CNT_CODE
+// CHECK-NEXT:       MEM_16BIT
+// CHECK-NEXT:       MEM_EXECUTE
+// CHECK-NEXT:       MEM_PURGEABLE
+// CHECK-NEXT:       MEM_READ
+// CHECK-NEXT:     ]
+// CHECK-NEXT:   }
+// CHECK:        Section {
+// CHECK:          Name: .xdata
+// CHECK:          RawDataSize: 120
+// CHECK:          RelocationCount: 1
+// CHECK:          Characteristics [
+// CHECK-NEXT:       ALIGN_4BYTES
+// CHECK-NEXT:       CNT_INITIALIZED_DATA
+// CHECK-NEXT:       MEM_READ
+// CHECK-NEXT:     ]
+// CHECK-NEXT:   }
+// CHECK:        Section {
+// CHECK:          Name: .pdata
+// CHECK:          RelocationCount: 10
+// CHECK:          Characteristics [
+// CHECK-NEXT:       ALIGN_4BYTES
+// CHECK-NEXT:       CNT_INITIALIZED_DATA
+// CHECK-NEXT:       MEM_READ
+// CHECK-NEXT:     ]
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]
+
+// CHECK-NEXT: Relocations [
+// CHECK-NEXT:   Section (1) .text {
+// CHECK-NEXT:     0x5C IMAGE_REL_ARM_BRANCH24T tailcall
+// CHECK-NEXT:   }
+// CHECK-NEXT:   Section (4) .xdata {
+// CHECK-NEXT:     0x38 IMAGE_REL_ARM_ADDR32NB __C_specific_handler
+// CHECK-NEXT:   }
+// CHECK-NEXT:   Section (5) .pdata {
+// CHECK-NEXT:     0x0 IMAGE_REL_ARM_ADDR32NB .text
+// CHECK-NEXT:     0x4 IMAGE_REL_ARM_ADDR32NB .xdata
+// CHECK-NEXT:     0x8 IMAGE_REL_ARM_ADDR32NB .text
+// CHECK-NEXT:     0xC IMAGE_REL_ARM_ADDR32NB .xdata
+// CHECK-NEXT:     0x10 IMAGE_REL_ARM_ADDR32NB .text
+// CHECK-NEXT:     0x14 IMAGE_REL_ARM_ADDR32NB .xdata
+// CHECK-NEXT:     0x18 IMAGE_REL_ARM_ADDR32NB .text
+// CHECK-NEXT:     0x1C IMAGE_REL_ARM_ADDR32NB .xdata
+// CHECK-NEXT:     0x20 IMAGE_REL_ARM_ADDR32NB .text
+// CHECK-NEXT:     0x24 IMAGE_REL_ARM_ADDR32NB .xdata
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]
+
+// CHECK-NEXT: UnwindInformation [
+// CHECK-NEXT:   RuntimeFunction {
+// CHECK-NEXT:     Function: func
+// CHECK-NEXT:     ExceptionRecord: .xdata
+// CHECK-NEXT:     ExceptionData {
+// CHECK-NEXT:       FunctionLength: 86
+// CHECK:            Fragment: No
+// CHECK:            Prologue [
+// CHECK-NEXT:         0xed 0xf8           ; push {r3-r7, lr}
+// CHECK-NEXT:         0xf6 0x27           ; vpush {d18-d23}
+// CHECK-NEXT:         0xf5 0x7e           ; vpush {d7-d14}
+// CHECK-NEXT:         0xfb                ; nop
+// CHECK-NEXT:         0xce                ; mov r14, sp
+// CHECK-NEXT:         0xe3                ; vpush {d8-d11}
+// CHECK-NEXT:         0xe6                ; vpush {d8-d14}
+// CHECK-NEXT:         0xed 0xf8           ; push {r3-r7, lr}
+// CHECK-NEXT:         0xbd 0x50           ; push.w {r4, r6, r8, r10-r12, lr}
+// CHECK-NEXT:         0xd7                ; push {r4-r7, lr}
+// CHECK-NEXT:         0xdd                ; push.w {r4-r9, lr}
+// CHECK-NEXT:         0xfa 0x01 0x00 0x00 ; sub.w sp, sp, #(65536 * 4)
+// CHECK-NEXT:         0xfc                ; nop.w
+// CHECK-NEXT:         0xfc                ; nop.w
+// CHECK-NEXT:         0xf9 0x04 0x00      ; sub.w sp, sp, #(1024 * 4)
+// CHECK-NEXT:         0xe8 0x80           ; sub.w sp, #(128 * 4)
+// CHECK-NEXT:         0xe8 0x80           ; sub.w sp, #(128 * 4)
+// CHECK-NEXT:         0x06                ; sub sp, #(6 * 4)
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       EpilogueScopes [
+// CHECK-NEXT:         EpilogueScope {
+// CHECK-NEXT:           StartOffset: 31
+// CHECK-NEXT:           Condition: 14
+// CHECK-NEXT:           EpilogueStartIndex: 31
+// CHECK-NEXT:           Opcodes [
+// CHECK-NEXT:             0xfc                ; nop.w
+// CHECK-NEXT:             0xf7 0x00 0x80      ; add sp, sp, #(128 * 4)
+// CHECK-NEXT:             0xfc                ; nop.w
+// CHECK-NEXT:             0xfc                ; nop.w
+// CHECK-NEXT:             0xf8 0x01 0x00 0x00 ; add sp, sp, #(65536 * 4)
+// CHECK-NEXT:             0x06                ; add sp, #(6 * 4)
+// CHECK-NEXT:             0xef 0x04           ; ldr.w lr, [sp], #16
+// CHECK-NEXT:             0xfd                ; bx <reg>
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       ExceptionHandler [
+// CHECK-NEXT:         Routine: __C_specific_handler
+// CHECK-NEXT:         Parameter: 0x0
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT:   RuntimeFunction {
+// CHECK-NEXT:     Function: func2
+// CHECK:            Prologue [
+// CHECK-NEXT:         0xd3                ; push {r4-r7}
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       EpilogueScopes [
+// CHECK-NEXT:         EpilogueScope {
+// CHECK:                Opcodes [
+// CHECK-NEXT:             0xd2                ; pop {r4-r6}
+// CHECK-NEXT:             0xfe                ; b.w <target>
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT:   RuntimeFunction {
+// CHECK-NEXT:     Function: func3
+// CHECK:            FunctionLength: 8
+// CHECK:            Prologue [
+// CHECK-NEXT:         0xd5                ; push {r4-r5, lr}
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       EpilogueScopes [
+// CHECK-NEXT:         EpilogueScope {
+// CHECK-NEXT:           StartOffset: 3
+// CHECK-NEXT:           Condition: 14
+// CHECK-NEXT:           EpilogueStartIndex: 2
+// CHECK-NEXT:           Opcodes [
+// CHECK-NEXT:             0xd6                ; pop {r4-r6, pc}
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT:   RuntimeFunction {
+// CHECK-NEXT:     Function: fragment
+// CHECK:            FunctionLength: 6
+// CHECK:            Fragment: Yes
+// CHECK:            Prologue [
+// CHECK-NEXT:         0xcb                ; mov r11, sp
+// CHECK-NEXT:         0x10                ; sub sp, #(16 * 4)
+// CHECK-NEXT:         0xd5                ; push {r4-r5, lr}
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       EpilogueScopes [
+// CHECK-NEXT:         EpilogueScope {
+// CHECK-NEXT:           StartOffset: 1
+// CHECK-NEXT:           Condition: 14
+// CHECK-NEXT:           EpilogueStartIndex: 4
+// CHECK-NEXT:           Opcodes [
+// CHECK-NEXT:             0x10                ; add sp, #(16 * 4)
+// CHECK-NEXT:             0xd5                ; pop {r4-r5, pc}
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT:   RuntimeFunction {
+// CHECK-NEXT:     Function: condepilog
+// CHECK:            FunctionLength: 8
+// CHECK:            Prologue [
+// CHECK-NEXT:         0xd5                ; push {r4-r5, lr}
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       EpilogueScopes [
+// CHECK-NEXT:         EpilogueScope {
+// CHECK-NEXT:           StartOffset: 3
+// CHECK-NEXT:           Condition: 10
+// CHECK-NEXT:           EpilogueStartIndex: 2
+// CHECK-NEXT:           Opcodes [
+// CHECK-NEXT:             0xd5                ; pop {r4-r5, pc}
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]
+
+        .text
+        .syntax unified
+        .globl func
+        .def func
+        .scl 2
+        .type 32
+        .endef
+        .seh_proc func
+func:
+        sub sp, sp, #24
+        .seh_stackalloc 24
+        sub sp, sp, #512
+        .seh_stackalloc_w 512
+        sub sp, sp, #512
+        .seh_stackalloc_w 512
+        sub sp, sp, #4096
+        .seh_stackalloc_w 4096
+        movw r7, #0
+        .seh_nop_w
+        movt r7, #0x4 // 0x40000
+        .seh_nop_w
+        sub sp, sp, r7
+        .seh_stackalloc_w 0x40000
+        push {r4-r8,lr}
+        .seh_save_regs_w {r4-r9,lr}
+        push {r4-r7,lr}
+        .seh_save_regs {r4-r7,lr}
+        push {r4,r6,r8,r10,r11,r12,lr}
+        .seh_save_regs_w {r4,r6,r8,r10,r11,r12,lr}
+        push {r3-r7,lr}
+        .seh_save_regs {r3-r7,lr}
+        vpush {d8-d14}
+        .seh_save_fregs {d8-d14}
+        vpush {q4-q5}
+        .seh_save_fregs {q4-q5}
+        mov lr, sp
+        .seh_save_sp lr
+        nop
+        .seh_nop
+        vpush {d7-d14}
+        .seh_save_fregs {d7-d14}
+        vpush {d18-d23}
+        .seh_save_fregs {d18-d23}
+        push {r3-r7,lr}
+        .seh_custom 0xed, 0xf8
+        .seh_endprologue
+        nop
+        .seh_startepilogue
+        mov r7, #512
+        .seh_nop_w
+        add sp, sp, r7
+        .seh_stackalloc 512
+        movw r7, #0
+        .seh_nop_w
+        movt r7, #0x4 // 0x40000
+        .seh_nop_w
+        add sp, sp, r7
+        .seh_stackalloc 0x40000
+        add sp, sp, #24
+        .seh_stackalloc 24
+        ldr lr, [sp], #16
+        .seh_save_lr 16
+        bx lr
+        .seh_nop
+        .seh_endepilogue
+        .seh_handler __C_specific_handler, %except
+        .seh_handlerdata
+        .long 0
+        .text
+        .seh_endproc
+
+        .seh_proc func2
+func2:
+        push {r4-r7}
+        .seh_save_regs {r4-r7}
+        .seh_endprologue
+        nop
+        .seh_startepilogue
+        pop {r4-r6}
+        .seh_save_regs {r4-r6}
+        b.w tailcall
+        .seh_nop_w
+        .seh_endepilogue
+        .seh_endproc
+
+        .seh_proc func3
+func3:
+        push {r4-r5,lr}
+        .seh_save_regs {r4-r5,lr}
+        .seh_endprologue
+        nop
+        // The p2align causes the length of the function to be unknown.
+        .p2align 1
+        nop
+        .seh_startepilogue
+        pop {r4-r6,pc}
+        .seh_save_regs {r4-r6,pc}
+        .seh_endepilogue
+        .seh_endproc
+
+        .seh_proc fragment
+fragment:
+        // Prologue opcodes without matching instructions
+        .seh_save_regs {r4-r5,lr}
+        .seh_stackalloc 64
+        .seh_save_sp r11
+        .seh_endprologue_fragment
+        nop
+        .seh_startepilogue
+        add sp, sp, #64
+        .seh_stackalloc 64
+        pop {r4-r5,pc}
+        .seh_save_regs {r4-r5,pc}
+        .seh_endepilogue
+        .seh_endproc
+
+        .seh_proc condepilog
+condepilog:
+        push {r4-r5,lr}
+        .seh_save_regs {r4-r5,lr}
+        .seh_endprologue
+        nop
+        it ge
+        .seh_startepilogue_cond ge
+        popge {r4-r5,pc}
+        .seh_save_regs {r4-r5,pc}
+        .seh_endepilogue
+        .seh_endproc
+
+        // Function with no .seh directives; no pdata/xdata entries are
+        // generated.
+        .globl smallFunc
+        .def smallFunc
+        .scl 2
+        .type 32
+        .endef
+        .seh_proc smallFunc
+smallFunc:
+        bx lr
+        .seh_endproc
+
+        // Function with no .seh directives, but with .seh_handlerdata.
+        // No xdata/pdata entries are generated, but the custom handler data
+        // (the .long after .seh_handlerdata) is left orphaned in the xdata
+        // section.
+        .globl handlerFunc
+        .def handlerFunc
+        .scl 2
+        .type 32
+        .endef
+        .seh_proc handlerFunc
+handlerFunc:
+        bx lr
+        .seh_handler __C_specific_handler, %except
+        .seh_handlerdata
+        .long 0
+        .text
+        .seh_endproc