Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -255,6 +255,8 @@
     return true;
   case Triple::ELF:
     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
+  case Triple::GOFF:
+    llvm::report_fatal_error("ASan not implemented for GOFF.");
   case Triple::XCOFF:
     llvm::report_fatal_error("ASan not implemented for XCOFF.");
   case Triple::Wasm:
Index: clang/lib/CodeGen/CGObjCMac.cpp
===================================================================
--- clang/lib/CodeGen/CGObjCMac.cpp
+++ clang/lib/CodeGen/CGObjCMac.cpp
@@ -5107,6 +5107,7 @@
     return ("." + Section.substr(2) + "$B").str();
   case llvm::Triple::Wasm:
   case llvm::Triple::XCOFF:
+  case llvm::Triple::GOFF:
     llvm::report_fatal_error(
         "Objective-C support is unimplemented for object file format.");
   }
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -4903,6 +4903,8 @@
     llvm_unreachable("unknown file format");
   case llvm::Triple::XCOFF:
     llvm_unreachable("XCOFF is not yet implemented");
+  case llvm::Triple::GOFF:
+    llvm_unreachable("GOFF is not yet implemented");
   case llvm::Triple::COFF:
   case llvm::Triple::ELF:
   case llvm::Triple::Wasm:
Index: llvm/include/llvm/ADT/Triple.h
===================================================================
--- llvm/include/llvm/ADT/Triple.h
+++ llvm/include/llvm/ADT/Triple.h
@@ -173,6 +173,7 @@
     OpenBSD,
     Solaris,
     Win32,
+    ZOS,
     Haiku,
     Minix,
     RTEMS,
@@ -225,6 +226,7 @@
 
     COFF,
     ELF,
+    GOFF,
     MachO,
     Wasm,
     XCOFF,
@@ -479,6 +481,10 @@
     return getSubArch() == Triple::ARMSubArch_v7k;
   }
 
+  bool isOSzOS() const {
+    return getOS() == Triple::ZOS;
+  }
+
   /// isOSDarwin - Is this a "Darwin" OS (macOS, iOS, tvOS or watchOS).
   bool isOSDarwin() const {
     return isMacOSX() || isiOS() || isWatchOS();
@@ -631,6 +637,11 @@
     return getObjectFormat() == Triple::COFF;
   }
 
+  /// Tests whether the OS uses the GOFF binary format.
+  bool isOSBinFormatGOFF() const {
+    return getObjectFormat() == Triple::GOFF;
+  }
+
   /// Tests whether the environment is MachO.
   bool isOSBinFormatMachO() const {
     return getObjectFormat() == Triple::MachO;
Index: llvm/include/llvm/Support/TargetRegistry.h
===================================================================
--- llvm/include/llvm/Support/TargetRegistry.h
+++ llvm/include/llvm/Support/TargetRegistry.h
@@ -514,6 +514,8 @@
       S = createXCOFFStreamer(Ctx, std::move(TAB), std::move(OW),
                               std::move(Emitter), RelaxAll);
       break;
+    case Triple::GOFF:
+      report_fatal_error("GOFF MCObjectStreamer not implemented yet."); 
     }
     if (ObjectTargetStreamerCtorFn)
       ObjectTargetStreamerCtorFn(*S, STI);
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -4728,6 +4728,8 @@
   case Triple::Wasm:
   case Triple::UnknownObjectFormat:
     return ".llvmbc";
+  case Triple::GOFF:
+    llvm_unreachable("GOFF is not yet implemented");
   case Triple::XCOFF:
     llvm_unreachable("XCOFF is not yet implemented");
     break;
@@ -4744,6 +4746,8 @@
   case Triple::Wasm:
   case Triple::UnknownObjectFormat:
     return ".llvmcmd";
+  case Triple::GOFF:
+    llvm_unreachable("GOFF is not yet implemented");
   case Triple::XCOFF:
     llvm_unreachable("XCOFF is not yet implemented");
     break;
Index: llvm/lib/MC/MCObjectFileInfo.cpp
===================================================================
--- llvm/lib/MC/MCObjectFileInfo.cpp
+++ llvm/lib/MC/MCObjectFileInfo.cpp
@@ -908,6 +908,8 @@
     Env = IsXCOFF;
     initXCOFFMCObjectFileInfo(TT);
     break;
+  case Triple::GOFF:
+    report_fatal_error("Cannot initialize MC for GOFF object file format.");
   case Triple::UnknownObjectFormat:
     report_fatal_error("Cannot initialize MC for unknown object file format.");
     break;
@@ -924,6 +926,7 @@
   case Triple::COFF:
   case Triple::Wasm:
   case Triple::XCOFF:
+  case Triple::GOFF:
   case Triple::UnknownObjectFormat:
     report_fatal_error("Cannot get DWARF comdat section for this object file "
                        "format: not implemented.");
Index: llvm/lib/Support/Triple.cpp
===================================================================
--- llvm/lib/Support/Triple.cpp
+++ llvm/lib/Support/Triple.cpp
@@ -217,6 +217,7 @@
   case WASI: return "wasi";
   case WatchOS: return "watchos";
   case Win32: return "windows";
+  case ZOS: return "zos";
   }
 
   llvm_unreachable("Invalid OSType");
@@ -503,6 +504,7 @@
     .StartsWith("solaris", Triple::Solaris)
     .StartsWith("win32", Triple::Win32)
     .StartsWith("windows", Triple::Win32)
+    .StartsWith("zos", Triple::ZOS)
     .StartsWith("haiku", Triple::Haiku)
     .StartsWith("minix", Triple::Minix)
     .StartsWith("rtems", Triple::RTEMS)
@@ -557,6 +559,7 @@
     .EndsWith("xcoff", Triple::XCOFF)
     .EndsWith("coff", Triple::COFF)
     .EndsWith("elf", Triple::ELF)
+    .EndsWith("goff", Triple::GOFF)
     .EndsWith("macho", Triple::MachO)
     .EndsWith("wasm", Triple::Wasm)
     .Default(Triple::UnknownObjectFormat);
@@ -651,6 +654,7 @@
   case Triple::MachO: return "macho";
   case Triple::Wasm:  return "wasm";
   case Triple::XCOFF: return "xcoff";
+  case Triple::GOFF:  return "goff";
   }
   llvm_unreachable("unknown object format type");
 }
@@ -705,7 +709,6 @@
   case Triple::sparcv9:
   case Triple::spir64:
   case Triple::spir:
-  case Triple::systemz:
   case Triple::tce:
   case Triple::tcele:
   case Triple::thumbeb:
@@ -719,6 +722,11 @@
       return Triple::XCOFF;
     return Triple::ELF;
 
+  case Triple::systemz:
+    if (T.getOS() == Triple::ZOS)
+      return Triple::GOFF;
+    return Triple::ELF;
+
   case Triple::wasm32:
   case Triple::wasm64:
     return Triple::Wasm;
Index: llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1961,6 +1961,7 @@
   case Triple::MachO: return "__DATA,__asan_globals,regular";
   case Triple::Wasm:
   case Triple::XCOFF:
+  case Triple::GOFF:
     report_fatal_error(
         "ModuleAddressSanitizer not implemented for object file format.");
   case Triple::UnknownObjectFormat:
Index: llvm/unittests/ADT/TripleTest.cpp
===================================================================
--- llvm/unittests/ADT/TripleTest.cpp
+++ llvm/unittests/ADT/TripleTest.cpp
@@ -170,6 +170,18 @@
   EXPECT_EQ(Triple::FreeBSD, T.getOS());
   EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
 
+  T = Triple("s390x-ibm-zos");
+  EXPECT_EQ(Triple::systemz, T.getArch());
+  EXPECT_EQ(Triple::IBM, T.getVendor());
+  EXPECT_EQ(Triple::ZOS, T.getOS());
+  EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
+
+  T = Triple("systemz-ibm-zos");
+  EXPECT_EQ(Triple::systemz, T.getArch());
+  EXPECT_EQ(Triple::IBM, T.getVendor());
+  EXPECT_EQ(Triple::ZOS, T.getOS());
+  EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
+
   T = Triple("arm-none-none-eabi");
   EXPECT_EQ(Triple::arm, T.getArch());
   EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
@@ -1289,6 +1301,15 @@
   EXPECT_EQ(Triple::ELF, Triple("i686-pc-windows-msvc-elf").getObjectFormat());
   EXPECT_EQ(Triple::ELF, Triple("i686-pc-cygwin-elf").getObjectFormat());
 
+  EXPECT_EQ(Triple::ELF, Triple("systemz-ibm-linux").getObjectFormat());
+  EXPECT_EQ(Triple::ELF, Triple("systemz-ibm-unknown").getObjectFormat());
+
+  EXPECT_EQ(Triple::GOFF, Triple("s390x-ibm-zos").getObjectFormat());
+  EXPECT_EQ(Triple::GOFF, Triple("systemz-ibm-zos").getObjectFormat());
+  EXPECT_EQ(Triple::GOFF, Triple("s390x-ibm-zos-goff").getObjectFormat());
+  EXPECT_EQ(Triple::GOFF, Triple("s390x-unknown-zos-goff").getObjectFormat());
+  EXPECT_EQ(Triple::GOFF, Triple("s390x---goff").getObjectFormat());
+
   EXPECT_EQ(Triple::Wasm, Triple("wasm32-unknown-unknown").getObjectFormat());
   EXPECT_EQ(Triple::Wasm, Triple("wasm64-unknown-unknown").getObjectFormat());
   EXPECT_EQ(Triple::Wasm, Triple("wasm32-wasi").getObjectFormat());
@@ -1335,6 +1356,9 @@
 
   T.setObjectFormat(Triple::XCOFF);
   EXPECT_EQ(Triple::XCOFF, T.getObjectFormat());
+
+  T.setObjectFormat(Triple::GOFF);
+  EXPECT_EQ(Triple::GOFF, T.getObjectFormat());
 }
 
 TEST(TripleTest, NormalizeWindows) {