diff --git a/llvm/lib/Demangle/Compiler.h b/llvm/lib/Demangle/Compiler.h
new file mode 100644
index 0000000..248d6e3
--- /dev/null
+++ b/llvm/lib/Demangle/Compiler.h
@@ -0,0 +1,93 @@
+//===--- Compiler.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//
+// This file contains a variety of feature test macros copied from
+// include/llvm/Support/Compiler.h so that LLVMDemangle does not need to take
+// a dependency on LLVMSupport.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_COMPILER_H
+#define LLVM_DEMANGLE_COMPILER_H
+
+#ifdef _MSC_VER
+// snprintf is implemented in VS 2015
+#if _MSC_VER < 1900
+#define snprintf _snprintf_s
+#endif
+#endif
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#ifndef __has_cpp_attribute
+#define __has_cpp_attribute(x) 0
+#endif
+
+#ifndef __has_attribute
+#define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef LLVM_GNUC_PREREQ
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
+#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >=          \
+   ((maj) << 20) + ((min) << 10) + (patch))
+#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
+#else
+#define LLVM_GNUC_PREREQ(maj, min, patch) 0
+#endif
+#endif
+
+#if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0)
+#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define LLVM_ATTRIBUTE_USED
+#endif
+
+#if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0)
+#define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+#define LLVM_BUILTIN_UNREACHABLE __assume(false)
+#endif
+
+#if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0)
+#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
+#else
+#define LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
+#else
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+#if __cplusplus > 201402L && __has_cpp_attribute(fallthrough)
+#define LLVM_FALLTHROUGH [[fallthrough]]
+#elif __has_cpp_attribute(gnu::fallthrough)
+#define LLVM_FALLTHROUGH [[gnu::fallthrough]]
+#elif !__cplusplus
+// Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious
+// error when __has_cpp_attribute is given a scoped attribute in C mode.
+#define LLVM_FALLTHROUGH
+#elif __has_cpp_attribute(clang::fallthrough)
+#define LLVM_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define LLVM_FALLTHROUGH
+#endif
+
+#endif