diff --git a/llvm/lib/Target/Z80/GISel/Z80CallLowering.cpp b/llvm/lib/Target/Z80/GISel/Z80CallLowering.cpp
index f3c86443548f1..c65862c094013 100644
--- a/llvm/lib/Target/Z80/GISel/Z80CallLowering.cpp
+++ b/llvm/lib/Target/Z80/GISel/Z80CallLowering.cpp
@@ -29,8 +29,8 @@
 using namespace llvm;
 using namespace MIPatternMatch;
 
-cl::opt<bool> ReturnSRet("z80-return-sret", cl::desc("Return sret pointers"),
-                         cl::init(true), cl::Hidden);
+static cl::opt<bool> ReturnSRet("z80-return-sret", cl::desc("Return sret pointers"),
+                                cl::init(true), cl::Hidden);
 
 #define DEBUG_TYPE "z80-call-lowering"
 
diff --git a/llvm/lib/Target/Z80/MCTargetDesc/Z80MCAsmInfo.cpp b/llvm/lib/Target/Z80/MCTargetDesc/Z80MCAsmInfo.cpp
index f47c4d8fa7e4f..d9f1684bd8cfc 100644
--- a/llvm/lib/Target/Z80/MCTargetDesc/Z80MCAsmInfo.cpp
+++ b/llvm/lib/Target/Z80/MCTargetDesc/Z80MCAsmInfo.cpp
@@ -24,54 +24,66 @@ static cl::opt<bool> EscapeNonPrint(
         "Avoid outputting non-printable ascii characters to assembly files."),
     cl::Hidden);
 
+cl::opt<bool> Z80GasStyle(
+    "z80-gas-style",
+    cl::desc("Use GAS style assembly syntax instead of FASMG style."),
+    cl::NotHidden);
+
 void Z80MCAsmInfoELF::anchor() { }
 
 Z80MCAsmInfoELF::Z80MCAsmInfoELF(const Triple &T) {
   bool Is16Bit = T.isArch16Bit() || T.getEnvironment() == Triple::CODE16;
   CodePointerSize = CalleeSaveStackSlotSize = Is16Bit ? 2 : 3;
   MaxInstLength = 6;
-  DollarIsPC = true;
-  SeparatorString = nullptr;
-  CommentString = ";";
-  PrivateGlobalPrefix = PrivateLabelPrefix = "";
-  Code16Directive = "assume\tadl = 0";
-  Code24Directive = "assume\tadl = 1";
-  Code32Directive = Code64Directive = nullptr;
-  AssemblerDialect = !Is16Bit;
-  SupportsQuotedNames = false;
-  ZeroDirective = AscizDirective = nullptr;
-  BlockSeparator = " dup ";
-  AsciiDirective = ByteListDirective = Data8bitsDirective = "\tdb\t";
-  NumberLiteralSyntax = ANLS_PlainDecimal;
-  CharacterLiteralSyntax = ACLS_SingleQuotes;
-  HasPairedDoubleQuoteStringConstants = true;
-  HasBackslashEscapesInStringConstants = false;
-  StringConstantsEscapeNonPrint = EscapeNonPrint;
-  StringConstantsRequiredEscapes = {"\n\r\32", 4}; // include null
-  Data16bitsDirective = "\tdw\t";
-  Data24bitsDirective = "\tdl\t";
-  Data32bitsDirective = "\tdd\t";
-  Data64bitsDirective = "\tdq\t";
-  DataULEB128Directive = "\tuleb128\t";
-  DataSLEB128Directive = "\tsleb128\t";
-  SectionDirective = "\tsection\t";
-  AlwaysChangeSection = true;
-  GlobalDirective = "\tpublic\t";
-  LGloblDirective = "\tprivate\t";
-  SetDirective = "\tlabel\t";
-  SetSeparator = " at ";
-  HasFunctionAlignment = false;
-  HasDotTypeDotSizeDirective = false;
-  IdentDirective = "\tident\t";
-  WeakDirective = "\tweak\t";
-  UseIntegratedAssembler = false;
-  UseLogicalShr = false;
-  HasSingleParameterDotFile = false;
-  SupportsDebugInformation = SupportsCFI = true;
-  ExceptionsType = ExceptionHandling::SjLj;
-  DwarfFileDirective = "\tfile\t";
-  DwarfLocDirective = "\tloc\t";
-  DwarfCFIDirectivePrefix = "\tcfi_";
+
+  if (!Z80GasStyle) {
+    DollarIsPC = true;
+    SeparatorString = nullptr;
+    CommentString = ";";
+    PrivateGlobalPrefix = PrivateLabelPrefix = "";
+    Code16Directive = "assume\tadl = 0";
+    Code24Directive = "assume\tadl = 1";
+    Code32Directive = Code64Directive = nullptr;
+    AssemblerDialect = !Is16Bit;
+    SupportsQuotedNames = false;
+    ZeroDirective = AscizDirective = nullptr;
+    BlockSeparator = " dup ";
+    AsciiDirective = ByteListDirective = Data8bitsDirective = "\tdb\t";
+    NumberLiteralSyntax = ANLS_PlainDecimal;
+    CharacterLiteralSyntax = ACLS_SingleQuotes;
+    HasPairedDoubleQuoteStringConstants = true;
+    HasBackslashEscapesInStringConstants = false;
+    StringConstantsEscapeNonPrint = EscapeNonPrint;
+    StringConstantsRequiredEscapes = {"\n\r\32", 4}; // include null
+    Data16bitsDirective = "\tdw\t";
+    Data24bitsDirective = "\tdl\t";
+    Data32bitsDirective = "\tdd\t";
+    Data64bitsDirective = "\tdq\t";
+    DataULEB128Directive = "\tuleb128\t";
+    DataSLEB128Directive = "\tsleb128\t";
+    SectionDirective = "\tsection\t";
+    AlwaysChangeSection = true;
+    GlobalDirective = "\tpublic\t";
+    LGloblDirective = "\tprivate\t";
+    SetDirective = "\tlabel\t";
+    SetSeparator = " at ";
+    HasFunctionAlignment = false;
+    HasDotTypeDotSizeDirective = false;
+    IdentDirective = "\tident\t";
+    WeakDirective = "\tweak\t";
+    UseIntegratedAssembler = false;
+    UseLogicalShr = false;
+    HasSingleParameterDotFile = false;
+    SupportsDebugInformation = SupportsCFI = true;
+    ExceptionsType = ExceptionHandling::SjLj;
+    DwarfFileDirective = "\tfile\t";
+    DwarfLocDirective = "\tloc\t";
+    DwarfCFIDirectivePrefix = "\tcfi_";
+  } else {
+    CommentString = ";";
+    Code16Directive = Code24Directive = Code32Directive = Code64Directive = nullptr;
+    UseIntegratedAssembler = false;
+  }
 }
 
 MCSection *Z80MCAsmInfoELF::getNonexecutableStackSection(MCContext &Ctx) const {
@@ -79,7 +91,7 @@ MCSection *Z80MCAsmInfoELF::getNonexecutableStackSection(MCContext &Ctx) const {
 }
 
 bool Z80MCAsmInfoELF::isAcceptableChar(char C) const {
-  return MCAsmInfo::isAcceptableChar(C) || C == '%' || C == '^';
+  return Z80GasStyle ? MCAsmInfo::isAcceptableChar(C) : (MCAsmInfo::isAcceptableChar(C) || C == '%' || C == '^');
 }
 
 bool Z80MCAsmInfoELF::shouldOmitSectionDirective(StringRef SectionName) const {
@@ -89,10 +101,10 @@ bool Z80MCAsmInfoELF::shouldOmitSectionDirective(StringRef SectionName) const {
 const char *Z80MCAsmInfoELF::getBlockDirective(int64_t Size) const {
   switch (Size) {
   default: return nullptr;
-  case 1: return "\tdb\t";
-  case 2: return "\tdw\t";
-  case 3: return "\tdl\t";
-  case 4: return "\tdd\t";
+  case 1: return Z80GasStyle ? "\t.byte" : "\tdb\t";
+  case 2: return Z80GasStyle ? "\t.short" : "\tdw\t";
+  case 3: return Z80GasStyle ? "\t.long" : "\tdl\t";
+  case 4: return Z80GasStyle ? "\t.quad" : "\tdd\t";
   }
 }
 
diff --git a/llvm/lib/Target/Z80/MCTargetDesc/Z80TargetStreamer.cpp b/llvm/lib/Target/Z80/MCTargetDesc/Z80TargetStreamer.cpp
index ce2c3f3ea8c2c..6f63a3ed47817 100644
--- a/llvm/lib/Target/Z80/MCTargetDesc/Z80TargetStreamer.cpp
+++ b/llvm/lib/Target/Z80/MCTargetDesc/Z80TargetStreamer.cpp
@@ -14,10 +14,13 @@
 #include "Z80TargetStreamer.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormattedStream.h"
 
 using namespace llvm;
 
+extern cl::opt<bool> Z80GasStyle;
+
 Z80TargetStreamer::Z80TargetStreamer(MCStreamer &S)
     : MCTargetStreamer(S) {}
 
@@ -32,34 +35,34 @@ void Z80TargetAsmStreamer::emitLabel(MCSymbol *Symbol) {
 
 void Z80TargetAsmStreamer::emitAlign(Align Alignment) {
   if (auto Mask = Alignment.value() - 1)
-    OS << "\trb\t($$ - $) and " << Mask << '\n';
+    Z80GasStyle ? OS << "\t.skip\t($$ - $) and " << Mask << '\n' : OS << "\trb\t($$ - $) and " << Mask << '\n';
 }
 
 void Z80TargetAsmStreamer::emitBlock(uint64_t NumBytes) {
   if (NumBytes)
-    OS << "\trb\t" << NumBytes << '\n';
+    Z80GasStyle ? OS << "\t.skip\t" << NumBytes << '\n' : OS << "\trb\t" << NumBytes << '\n';
 }
 
 void Z80TargetAsmStreamer::emitLocal(MCSymbol *Symbol) {
-  OS << "\tprivate\t";
+  Z80GasStyle ? OS << "\t.local\t" : OS << "\tprivate\t";
   Symbol->print(OS, MAI);
   OS << '\n';
 }
 
 void Z80TargetAsmStreamer::emitWeakGlobal(MCSymbol *Symbol) {
-  OS << "\tweak\t";
+  Z80GasStyle ? OS << "\t.weak\t" : OS << "\tweak\t";
   Symbol->print(OS, MAI);
   OS << '\n';
 }
 
 void Z80TargetAsmStreamer::emitGlobal(MCSymbol *Symbol) {
-  OS << "\tpublic\t";
+  Z80GasStyle ? OS << "\t.global\t" : OS << "\tpublic\t";
   Symbol->print(OS, MAI);
   OS << '\n';
 }
 
 void Z80TargetAsmStreamer::emitExtern(MCSymbol *Symbol) {
-  OS << "\textern\t";
+  Z80GasStyle ? OS << "\t.extern\t" : OS << "\textern\t";
   Symbol->print(OS, MAI);
   OS << '\n';
 }