diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -575,6 +575,8 @@
       return new KFreeBSDTargetInfo<X86_64TargetInfo>(Triple, Opts);
     case llvm::Triple::Solaris:
       return new SolarisTargetInfo<X86_64TargetInfo>(Triple, Opts);
+    case llvm::Triple::UEFI:
+      return new UEFIX86_64TargetInfo(Triple, Opts);
     case llvm::Triple::Win32: {
       switch (Triple.getEnvironment()) {
       case llvm::Triple::Cygnus:
diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -848,6 +848,23 @@
   }
 };
 
+// UEFI target
+template <typename Target>
+class LLVM_LIBRARY_VISIBILITY UEFITargetInfo : public OSTargetInfo<Target> {
+protected:
+  void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
+                    MacroBuilder &Builder) const override {
+    Builder.defineMacro("__UEFI__");
+  }
+
+public:
+  UEFITargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
+      : OSTargetInfo<Target>(Triple, Opts) {
+    this->WCharType = TargetInfo::UnsignedShort;
+    this->WIntType = TargetInfo::UnsignedShort;
+  }
+};
+
 void addWindowsDefines(const llvm::Triple &Triple, const LangOptions &Opts,
                        MacroBuilder &Builder);
 
diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
--- a/clang/lib/Basic/Targets/X86.h
+++ b/clang/lib/Basic/Targets/X86.h
@@ -780,6 +780,61 @@
   bool hasBitIntType() const override { return true; }
 };
 
+// x86-64 UEFI target
+class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
+    : public UEFITargetInfo<X86_64TargetInfo> {
+public:
+  UEFIX86_64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
+      : UEFITargetInfo<X86_64TargetInfo>(Triple, Opts) {
+    LongWidth = LongAlign = 32;
+    DoubleAlign = LongLongAlign = 64;
+    IntMaxType = SignedLongLong;
+    Int64Type = SignedLongLong;
+    SizeType = UnsignedLongLong;
+    PtrDiffType = SignedLongLong;
+    IntPtrType = SignedLongLong;
+    LongDoubleWidth = LongDoubleAlign = 64;
+    LongDoubleFormat = &llvm::APFloat::IEEEdouble();
+  }
+
+  void getTargetDefines(const LangOptions &Opts,
+                        MacroBuilder &Builder) const override {
+    Builder.defineMacro("_M_X64", "100");
+    Builder.defineMacro("_M_AMD64", "100");
+  }
+
+  BuiltinVaListKind getBuiltinVaListKind() const override {
+    return TargetInfo::CharPtrBuiltinVaList;
+  }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_X86StdCall:
+    case CC_X86ThisCall:
+    case CC_X86FastCall:
+      return CCCR_Ignore;
+    case CC_C:
+    case CC_X86VectorCall:
+    case CC_IntelOclBicc:
+    case CC_PreserveMost:
+    case CC_PreserveAll:
+    case CC_X86_64SysV:
+    case CC_Swift:
+    case CC_SwiftAsync:
+    case CC_X86RegCall:
+    case CC_OpenCLKernel:
+      return CCCR_OK;
+    default:
+      return CCCR_Warning;
+    }
+  }
+
+  TargetInfo::CallingConvKind
+  getCallingConvKind(bool ClangABICompat4) const override {
+    return CCK_MicrosoftWin64;
+  }
+};
+
 // x86-64 Windows target
 class LLVM_LIBRARY_VISIBILITY WindowsX86_64TargetInfo
     : public WindowsTargetInfo<X86_64TargetInfo> {
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -6019,6 +6019,9 @@
     case llvm::Triple::Mesa3D:
       TC = std::make_unique<toolchains::AMDGPUToolChain>(*this, Target, Args);
       break;
+    case llvm::Triple::UEFI:
+      TC = std::make_unique<toolchains::MSVCToolChain>(*this, Target, Args); ////TODO(prabhukr): Replace with a new UEFI toolchain
+      break;
     case llvm::Triple::Win32:
       switch (Target.getEnvironment()) {
       default:
diff --git a/llvm/include/llvm/ADT/Triple.h b/llvm/include/llvm/ADT/Triple.h
--- a/llvm/include/llvm/ADT/Triple.h
+++ b/llvm/include/llvm/ADT/Triple.h
@@ -195,6 +195,7 @@
     NetBSD,
     OpenBSD,
     Solaris,
+    UEFI,
     Win32,
     ZOS,
     Haiku,
diff --git a/llvm/lib/Support/Triple.cpp b/llvm/lib/Support/Triple.cpp
--- a/llvm/lib/Support/Triple.cpp
+++ b/llvm/lib/Support/Triple.cpp
@@ -235,6 +235,7 @@
   case RTEMS: return "rtems";
   case Solaris: return "solaris";
   case TvOS: return "tvos";
+  case UEFI: return "uefi";
   case WASI: return "wasi";
   case WatchOS: return "watchos";
   case Win32: return "windows";
@@ -562,6 +563,7 @@
     .StartsWith("netbsd", Triple::NetBSD)
     .StartsWith("openbsd", Triple::OpenBSD)
     .StartsWith("solaris", Triple::Solaris)
+    .StartsWith("uefi", Triple::UEFI)
     .StartsWith("win32", Triple::Win32)
     .StartsWith("windows", Triple::Win32)
     .StartsWith("zos", Triple::ZOS)