Index: include/clang/Basic/BuiltinsAArch64.def
===================================================================
--- include/clang/Basic/BuiltinsAArch64.def
+++ include/clang/Basic/BuiltinsAArch64.def
@@ -14,6 +14,10 @@
 
 // The format of this database matches clang/Basic/Builtins.def.
 
+#if defined(BUILTIN) && !defined(LANGBUILTIN)
+#   define LANGBUILTIN(ID, TYPE, ATTRS, BUILTIN_LANG) BUILTIN(ID, TYPE, ATTRS)
+#endif
+
 // In libgcc
 BUILTIN(__clear_cache, "vv*v*", "i")
 
@@ -61,4 +65,9 @@
 BUILTIN(__builtin_arm_wsr64, "vcC*LUi", "nc")
 BUILTIN(__builtin_arm_wsrp, "vcC*vC*", "nc")
 
+LANGBUILTIN(__dmb, "vUi", "nc", ALL_MS_LANGUAGES)
+LANGBUILTIN(__dsb, "vUi", "nc", ALL_MS_LANGUAGES)
+LANGBUILTIN(__isb, "vUi", "nc", ALL_MS_LANGUAGES)
+
 #undef BUILTIN
+#undef LANGBUILTIN
Index: lib/Basic/Targets/AArch64.cpp
===================================================================
--- lib/Basic/Targets/AArch64.cpp
+++ lib/Basic/Targets/AArch64.cpp
@@ -27,6 +27,8 @@
 
 #define BUILTIN(ID, TYPE, ATTRS)                                               \
    {#ID, TYPE, ATTRS, nullptr, ALL_LANGUAGES, nullptr},
+#define LANGBUILTIN(ID, TYPE, ATTRS, LANG)                                     \
+  {#ID, TYPE, ATTRS, nullptr, LANG, nullptr},
 #include "clang/Basic/BuiltinsAArch64.def"
 };
 
Index: test/CodeGen/arm64-microsoft-intrinsics.c
===================================================================
--- /dev/null
+++ test/CodeGen/arm64-microsoft-intrinsics.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple arm64-windows -fms-compatibility -emit-llvm -o - %s \
+// RUN:    | FileCheck %s -check-prefix CHECK-MSVC
+
+// RUN: not %clang_cc1 -triple arm64-linux -Werror -S -o /dev/null %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-LINUX
+
+void check__dmb(void) {
+  __dmb(0);
+}
+
+// CHECK-MSVC: @llvm.aarch64.dmb(i32 0)
+// CHECK-LINUX: error: implicit declaration of function '__dmb'
+
+void check__dsb(void) {
+  __dsb(0);
+}
+
+// CHECK-MSVC: @llvm.aarch64.dsb(i32 0)
+// CHECK-LINUX: error: implicit declaration of function '__dsb'
+
+void check__isb(void) {
+  __isb(0);
+}
+
+// CHECK-MSVC: @llvm.aarch64.isb(i32 0)
+// CHECK-LINUX: error: implicit declaration of function '__isb'