diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -171,7 +171,7 @@
     return "-m:l";
   if (T.isOSBinFormatMachO())
     return "-m:o";
-  if (T.isOSWindows() && T.isOSBinFormatCOFF())
+  if ((T.isOSWindows() || T.isUEFI()) && T.isOSBinFormatCOFF())
     return T.getArch() == Triple::x86 ? "-m:x" : "-m:w";
   if (T.isOSBinFormatXCOFF())
     return "-m:a";
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -799,6 +799,8 @@
   case Triple::x86_64:
     if (T.isOSWindows())
       return Triple::COFF;
+    else if (T.isUEFI())
+      return Triple::COFF;
     return Triple::ELF;
 
   case Triple::aarch64_be:
diff --git a/llvm/unittests/IR/DataLayoutTest.cpp b/llvm/unittests/IR/DataLayoutTest.cpp
--- a/llvm/unittests/IR/DataLayoutTest.cpp
+++ b/llvm/unittests/IR/DataLayoutTest.cpp
@@ -11,6 +11,7 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
+#include "llvm/TargetParser/Triple.h"
 #include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
 
@@ -104,4 +105,11 @@
   EXPECT_EQ(Align(4 * 8), DL->getPrefTypeAlign(V8F32Ty));
 }
 
+TEST(DataLayoutTest, UEFI) {
+  Triple TT = Triple("x86_64-unknown-uefi");
+
+  // Test UEFI X86_64 Mangling Component.
+  EXPECT_STREQ(DataLayout::getManglingComponent(TT), "-m:w");
+}
+
 } // anonymous namespace
diff --git a/llvm/unittests/TargetParser/TripleTest.cpp b/llvm/unittests/TargetParser/TripleTest.cpp
--- a/llvm/unittests/TargetParser/TripleTest.cpp
+++ b/llvm/unittests/TargetParser/TripleTest.cpp
@@ -462,6 +462,7 @@
   EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
   EXPECT_EQ(Triple::UEFI, T.getOS());
   EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
+  EXPECT_EQ(Triple::COFF, T.getObjectFormat());
 
   T = Triple("wasm32-unknown-unknown");
   EXPECT_EQ(Triple::wasm32, T.getArch());