Index: lib/interception/interception.h
===================================================================
--- lib/interception/interception.h
+++ lib/interception/interception.h
@@ -15,13 +15,13 @@
 #ifndef INTERCEPTION_H
 #define INTERCEPTION_H
 
-#if !defined(__linux__) && !defined(__FreeBSD__) && !defined(__APPLE__) && \
-    !defined(__NetBSD__) && !defined(_WIN32) && !defined(__Fuchsia__)
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
+#if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
+    !SANITIZER_NETBSD && !SANITIZER_WINDOWS && !SANITIZER_FUCHSIA
 # error "Interception doesn't work on this operating system."
 #endif
 
-#include "sanitizer_common/sanitizer_internal_defs.h"
-
 // These typedefs should be used only in the interceptor definitions to replace
 // the standard system types (e.g. SSIZE_T instead of ssize_t)
 typedef __sanitizer::uptr    SIZE_T;
@@ -87,7 +87,7 @@
 // As it's decided at compile time which functions are to be intercepted on Mac,
 // INTERCEPT_FUNCTION() is effectively a no-op on this system.
 
-#if defined(__APPLE__)
+#if SANITIZER_MAC
 #include <sys/cdefs.h>  // For __DARWIN_ALIAS_C().
 
 // Just a pair of pointers.
@@ -121,7 +121,7 @@
 # define INTERCEPTOR_ATTRIBUTE
 # define DECLARE_WRAPPER(ret_type, func, ...)
 
-#elif defined(_WIN32)
+#elif SANITIZER_WINDOWS
 # define WRAP(x) __asan_wrap_##x
 # define WRAPPER_NAME(x) "__asan_wrap_"#x
 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport)
@@ -129,7 +129,7 @@
     extern "C" ret_type func(__VA_ARGS__);
 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \
     extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__);
-#elif defined(__FreeBSD__) || defined(__NetBSD__)
+#elif SANITIZER_FREEBSD || SANITIZER_NETBSD
 # define WRAP(x) __interceptor_ ## x
 # define WRAPPER_NAME(x) "__interceptor_" #x
 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
@@ -139,7 +139,7 @@
 # define DECLARE_WRAPPER(ret_type, func, ...) \
      extern "C" ret_type func(__VA_ARGS__) \
      __attribute__((alias("__interceptor_" #func), visibility("default")));
-#elif !defined(__Fuchsia__)
+#elif !SANITIZER_FUCHSIA
 # define WRAP(x) __interceptor_ ## x
 # define WRAPPER_NAME(x) "__interceptor_" #x
 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
@@ -148,7 +148,7 @@
     __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
 #endif
 
-#if defined(__Fuchsia__)
+#if SANITIZER_FUCHSIA
 // There is no general interception at all on Fuchsia.
 // Sanitizer runtimes just define functions directly to preempt them,
 // and have bespoke ways to access the underlying libc functions.
@@ -156,7 +156,7 @@
 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 # define REAL(x) __unsanitized_##x
 # define DECLARE_REAL(ret_type, func, ...)
-#elif !defined(__APPLE__)
+#elif !SANITIZER_MAC
 # define PTR_TO_REAL(x) real_##x
 # define REAL(x) __interception::PTR_TO_REAL(x)
 # define FUNC_TYPE(x) x##_f
@@ -167,14 +167,14 @@
       extern FUNC_TYPE(func) PTR_TO_REAL(func); \
     }
 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
-#else  // __APPLE__
+#else  // SANITIZER_MAC
 # define REAL(x) x
 # define DECLARE_REAL(ret_type, func, ...) \
     extern "C" ret_type func(__VA_ARGS__);
 # define ASSIGN_REAL(x, y)
-#endif  // __APPLE__
+#endif  // SANITIZER_MAC
 
-#if !defined(__Fuchsia__)
+#if !SANITIZER_FUCHSIA
 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
   DECLARE_REAL(ret_type, func, __VA_ARGS__) \
   extern "C" ret_type WRAP(func)(__VA_ARGS__);
@@ -186,7 +186,7 @@
 // macros does its job. In exceptional cases you may need to call REAL(foo)
 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
 // foo with an interceptor for other function.
-#if !defined(__APPLE__) && !defined(__Fuchsia__)
+#if !SANITIZER_MAC && !SANITIZER_FUCHSIA
 # define DEFINE_REAL(ret_type, func, ...) \
     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
     namespace __interception { \
@@ -196,7 +196,7 @@
 # define DEFINE_REAL(ret_type, func, ...)
 #endif
 
-#if defined(__Fuchsia__)
+#if SANITIZER_FUCHSIA
 
 // We need to define the __interceptor_func name just to get
 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
@@ -206,7 +206,7 @@
       __interceptor_##func(__VA_ARGS__);                                \
   extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
 
-#elif !defined(__APPLE__)
+#elif !SANITIZER_MAC
 
 #define INTERCEPTOR(ret_type, func, ...) \
   DEFINE_REAL(ret_type, func, __VA_ARGS__) \
@@ -219,7 +219,7 @@
 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
   INTERCEPTOR(ret_type, func, __VA_ARGS__)
 
-#else  // __APPLE__
+#else  // SANITIZER_MAC
 
 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
   extern "C" ret_type func(__VA_ARGS__) suffix; \
@@ -238,7 +238,7 @@
   INTERPOSER_2(overridee, WRAP(overrider))
 #endif
 
-#if defined(_WIN32)
+#if SANITIZER_WINDOWS
 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
     typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
     namespace __interception { \
@@ -264,17 +264,17 @@
 
 #define INCLUDED_FROM_INTERCEPTION_LIB
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__)
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
 # include "interception_linux.h"
 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
 # define INTERCEPT_FUNCTION_VER(func, symver) \
     INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
-#elif defined(__APPLE__)
+#elif SANITIZER_MAC
 # include "interception_mac.h"
 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
 # define INTERCEPT_FUNCTION_VER(func, symver) \
     INTERCEPT_FUNCTION_VER_MAC(func, symver)
-#elif defined(_WIN32)
+#elif SANITIZER_WINDOWS
 # include "interception_win.h"
 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
 # define INTERCEPT_FUNCTION_VER(func, symver) \
Index: lib/interception/interception_linux.h
===================================================================
--- lib/interception/interception_linux.h
+++ lib/interception/interception_linux.h
@@ -12,7 +12,7 @@
 // Linux-specific interception methods.
 //===----------------------------------------------------------------------===//
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__)
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
 
 #if !defined(INCLUDED_FROM_INTERCEPTION_LIB)
 # error "interception_linux.h should be included from interception library only"
@@ -34,14 +34,14 @@
       (::__interception::uptr) & (func),                                   \
       (::__interception::uptr) & WRAP(func))
 
-#if !defined(__ANDROID__)  // android does not have dlvsym
+#if !SANITIZER_ANDROID  // android does not have dlvsym
 #define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
   (::__interception::real_##func = (func##_f)(                \
        unsigned long)::__interception::GetFuncAddrVer(#func, symver))
 #else
 #define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
   INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
-#endif  // !defined(__ANDROID__)
+#endif  // !SANITIZER_ANDROID
 
 #endif  // INTERCEPTION_LINUX_H
-#endif  // __linux__ || __FreeBSD__ || __NetBSD__
+#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
Index: lib/interception/interception_linux.cc
===================================================================
--- lib/interception/interception_linux.cc
+++ lib/interception/interception_linux.cc
@@ -12,19 +12,20 @@
 // Linux-specific interception methods.
 //===----------------------------------------------------------------------===//
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__)
 #include "interception.h"
 
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
+
 #include <dlfcn.h>   // for dlsym() and dlvsym()
 
-#ifdef __NetBSD__
+#if SANITIZER_NETBSD
 #include "sanitizer_common/sanitizer_libc.h"
 #endif
 
 namespace __interception {
 bool GetRealFunctionAddress(const char *func_name, uptr *func_addr,
     uptr real, uptr wrapper) {
-#ifdef __NetBSD__
+#if SANITIZER_NETBSD
   // XXX: Find a better way to handle renames
   if (internal_strcmp(func_name, "sigaction") == 0) func_name = "__sigaction14";
 #endif
@@ -40,12 +41,12 @@
   return real == wrapper;
 }
 
-#if !defined(__ANDROID__)  // android does not have dlvsym
+#if !SANITIZER_ANDROID  // android does not have dlvsym
 void *GetFuncAddrVer(const char *func_name, const char *ver) {
   return dlvsym(RTLD_NEXT, func_name, ver);
 }
-#endif  // !defined(__ANDROID__)
+#endif  // !SANITIZER_ANDROID
 
 }  // namespace __interception
 
-#endif  // __linux__ || __FreeBSD__ || __NetBSD__
+#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
Index: lib/interception/interception_mac.h
===================================================================
--- lib/interception/interception_mac.h
+++ lib/interception/interception_mac.h
@@ -12,7 +12,7 @@
 // Mac-specific interception methods.
 //===----------------------------------------------------------------------===//
 
-#ifdef __APPLE__
+#if SANITIZER_MAC
 
 #if !defined(INCLUDED_FROM_INTERCEPTION_LIB)
 # error "interception_mac.h should be included from interception.h only"
@@ -25,4 +25,4 @@
 #define INTERCEPT_FUNCTION_VER_MAC(func, symver)
 
 #endif  // INTERCEPTION_MAC_H
-#endif  // __APPLE__
+#endif  // SANITIZER_MAC
Index: lib/interception/interception_mac.cc
===================================================================
--- lib/interception/interception_mac.cc
+++ lib/interception/interception_mac.cc
@@ -12,9 +12,8 @@
 // Mac-specific interception methods.
 //===----------------------------------------------------------------------===//
 
-#ifdef __APPLE__
-
 #include "interception.h"
 
+#if SANITIZER_MAC
 
-#endif  // __APPLE__
+#endif  // SANITIZER_MAC
Index: lib/interception/interception_type_test.cc
===================================================================
--- lib/interception/interception_type_test.cc
+++ lib/interception/interception_type_test.cc
@@ -12,9 +12,10 @@
 // Compile-time tests of the internal type definitions.
 //===----------------------------------------------------------------------===//
 
-#if defined(__linux__) || defined(__APPLE__)
+#include "interception.h"
 
-#include "interception.h"
+#if SANITIZER_LINUX || SANITIZER_MAC
+
 #include <sys/types.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -24,14 +25,14 @@
 COMPILER_CHECK(sizeof(::PTRDIFF_T) == sizeof(ptrdiff_t));
 COMPILER_CHECK(sizeof(::INTMAX_T) == sizeof(intmax_t));
 
-#ifndef __APPLE__
+#if !SANITIZER_MAC
 COMPILER_CHECK(sizeof(::OFF64_T) == sizeof(off64_t));
 #endif
 
 // The following are the cases when pread (and friends) is used instead of
 // pread64. In those cases we need OFF_T to match off_t. We don't care about the
 // rest (they depend on _FILE_OFFSET_BITS setting when building an application).
-# if defined(__ANDROID__) || !defined _FILE_OFFSET_BITS || \
+# if SANITIZER_ANDROID || !defined _FILE_OFFSET_BITS || \
   _FILE_OFFSET_BITS != 64
 COMPILER_CHECK(sizeof(::OFF_T) == sizeof(off_t));
 # endif
Index: lib/interception/interception_win.h
===================================================================
--- lib/interception/interception_win.h
+++ lib/interception/interception_win.h
@@ -12,7 +12,7 @@
 // Windows-specific interception methods.
 //===----------------------------------------------------------------------===//
 
-#ifdef _WIN32
+#if SANITIZER_WINDOWS
 
 #if !defined(INCLUDED_FROM_INTERCEPTION_LIB)
 # error "interception_win.h should be included from interception library only"
@@ -81,4 +81,4 @@
       (::__interception::uptr *)&REAL(func))
 
 #endif  // INTERCEPTION_WIN_H
-#endif  // _WIN32
+#endif  // SANITIZER_WINDOWS
Index: lib/interception/interception_win.cc
===================================================================
--- lib/interception/interception_win.cc
+++ lib/interception/interception_win.cc
@@ -125,9 +125,9 @@
 //                                      addr2:  .bytes <body>
 //===----------------------------------------------------------------------===//
 
-#ifdef _WIN32
+#include "interception.h"
 
-#include "interception.h"
+#if SANITIZER_WINDOWS
 #include "sanitizer_common/sanitizer_platform.h"
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
@@ -1013,4 +1013,4 @@
 
 }  // namespace __interception
 
-#endif  // _WIN32
+#endif  // SANITIZER_MAC