Index: lib/asan/asan_interceptors.h
===================================================================
--- lib/asan/asan_interceptors.h
+++ lib/asan/asan_interceptors.h
@@ -34,10 +34,10 @@
 
 }  // namespace __asan
 
-// There is no general interception at all on Fuchsia.
+// There is no general interception at all on Fuchsia and RTEMS.
 // Only the functions in asan_interceptors_memintrinsics.h are
 // really defined to replace libc functions.
-#if !SANITIZER_FUCHSIA
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 // Use macro to describe if specific function should be
 // intercepted on a given platform.
Index: lib/asan/asan_interceptors.cc
===================================================================
--- lib/asan/asan_interceptors.cc
+++ lib/asan/asan_interceptors.cc
@@ -24,10 +24,10 @@
 #include "lsan/lsan_common.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
-// There is no general interception at all on Fuchsia.
+// There is no general interception at all on Fuchsia and RTEMS.
 // Only the functions in asan_interceptors_memintrinsics.cc are
 // really defined to replace libc functions.
-#if !SANITIZER_FUCHSIA
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 #if SANITIZER_POSIX
 #include "sanitizer_common/sanitizer_posix.h"
Index: lib/asan/asan_internal.h
===================================================================
--- lib/asan/asan_internal.h
+++ lib/asan/asan_internal.h
@@ -36,7 +36,7 @@
 // If set, values like allocator chunk size, as well as defaults for some flags
 // will be changed towards less memory overhead.
 #ifndef ASAN_LOW_MEMORY
-# if SANITIZER_IOS || SANITIZER_ANDROID
+# if SANITIZER_IOS || SANITIZER_ANDROID || SANITIZER_RTEMS
 #  define ASAN_LOW_MEMORY 1
 # else
 #  define ASAN_LOW_MEMORY 0
@@ -78,7 +78,7 @@
 // asan_malloc_linux.cc / asan_malloc_mac.cc
 void ReplaceSystemMalloc();
 
-// asan_linux.cc / asan_mac.cc / asan_win.cc
+// asan_linux.cc / asan_mac.cc / asan_rtems.cc / asan_win.cc
 uptr FindDynamicShadowStart();
 void *AsanDoesNotSupportStaticLinkage();
 void AsanCheckDynamicRTPrereqs();
Index: lib/asan/asan_poisoning.h
===================================================================
--- lib/asan/asan_poisoning.h
+++ lib/asan/asan_poisoning.h
@@ -51,6 +51,9 @@
       // changed at all.  It doesn't currently have an efficient means
       // to zero a bunch of pages, but maybe we should add one.
       SANITIZER_FUCHSIA == 1 ||
+      // RTEMS doesn't have have pages, let alone a fast way to zero
+      // them, so default to memset.
+      SANITIZER_RTEMS == 1 ||
       shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
     REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
   } else {
Index: lib/asan/asan_shadow_setup.cc
===================================================================
--- lib/asan/asan_shadow_setup.cc
+++ lib/asan/asan_shadow_setup.cc
@@ -14,8 +14,9 @@
 
 #include "sanitizer_common/sanitizer_platform.h"
 
-// asan_fuchsia.cc has its own InitializeShadowMemory implementation.
-#if !SANITIZER_FUCHSIA
+// asan_fuchsia.cc and asan_rtems.cc have their own
+// InitializeShadowMemory implementation.
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 #include "asan_internal.h"
 #include "asan_mapping.h"
@@ -162,4 +163,4 @@
 
 }  // namespace __asan
 
-#endif  // !SANITIZER_FUCHSIA
+#endif  // !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
Index: lib/asan/asan_thread.cc
===================================================================
--- lib/asan/asan_thread.cc
+++ lib/asan/asan_thread.cc
@@ -236,9 +236,10 @@
           &local);
 }
 
-// Fuchsia doesn't use ThreadStart.
-// asan_fuchsia.c defines CreateMainThread and SetThreadStackAndTls.
-#if !SANITIZER_FUCHSIA
+// Fuchsia and RTEMS don't use ThreadStart.
+// asan_fuchsia.c/asan_rtems.c define CreateMainThread and
+// SetThreadStackAndTls.
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 thread_return_t AsanThread::ThreadStart(
     tid_t os_id, atomic_uintptr_t *signal_thread_is_registered) {
@@ -298,7 +299,7 @@
   CHECK(AddrIsInStack((uptr)&local));
 }
 
-#endif  // !SANITIZER_FUCHSIA
+#endif  // !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 void AsanThread::ClearShadowForThreadStackAndTLS() {
   PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
Index: lib/interception/interception.h
===================================================================
--- lib/interception/interception.h
+++ lib/interception/interception.h
@@ -19,7 +19,7 @@
 
 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
     !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \
-    !SANITIZER_FUCHSIA && !SANITIZER_SOLARIS
+    !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS
 # error "Interception doesn't work on this operating system."
 #endif
 
@@ -130,6 +130,11 @@
     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 SANITIZER_RTEMS
+# define WRAP(x) x
+# define WRAPPER_NAME(x) #x
+# define INTERCEPTOR_ATTRIBUTE
+# define DECLARE_WRAPPER(ret_type, func, ...)
 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
 # define WRAP(x) __interceptor_ ## x
 # define WRAPPER_NAME(x) "__interceptor_" #x
@@ -157,6 +162,10 @@
 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 # define REAL(x) __unsanitized_##x
 # define DECLARE_REAL(ret_type, func, ...)
+#elif SANITIZER_RTEMS
+# define REAL(x) __real_ ## x
+# define DECLARE_REAL(ret_type, func, ...) \
+    extern "C" ret_type REAL(func)(__VA_ARGS__);
 #elif !SANITIZER_MAC
 # define PTR_TO_REAL(x) real_##x
 # define REAL(x) __interception::PTR_TO_REAL(x)
@@ -175,7 +184,7 @@
 # define ASSIGN_REAL(x, y)
 #endif  // SANITIZER_MAC
 
-#if !SANITIZER_FUCHSIA
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
   DECLARE_REAL(ret_type, func, __VA_ARGS__) \
   extern "C" ret_type WRAP(func)(__VA_ARGS__);
@@ -187,7 +196,7 @@
 // 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 !SANITIZER_MAC && !SANITIZER_FUCHSIA
+#if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 # define DEFINE_REAL(ret_type, func, ...) \
     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
     namespace __interception { \
Index: lib/sanitizer_common/sanitizer_errno.h
===================================================================
--- lib/sanitizer_common/sanitizer_errno.h
+++ lib/sanitizer_common/sanitizer_errno.h
@@ -24,7 +24,8 @@
 
 #if SANITIZER_FREEBSD || SANITIZER_MAC
 #  define __errno_location __error
-#elif SANITIZER_ANDROID || SANITIZER_NETBSD || SANITIZER_OPENBSD
+#elif SANITIZER_ANDROID || SANITIZER_NETBSD || SANITIZER_OPENBSD || \
+  SANITIZER_RTEMS
 #  define __errno_location __errno
 #elif SANITIZER_SOLARIS
 #  define __errno_location ___errno
Index: lib/sanitizer_common/sanitizer_platform.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform.h
+++ lib/sanitizer_common/sanitizer_platform.h
@@ -15,7 +15,8 @@
 
 #if !defined(__linux__) && !defined(__FreeBSD__) && !defined(__NetBSD__) && \
   !defined(__OpenBSD__) && !defined(__APPLE__) && !defined(_WIN32) && \
-  !defined(__Fuchsia__) && !(defined(__sun__) && defined(__svr4__))
+  !defined(__Fuchsia__) && !defined(__rtems__) && \
+  !(defined(__sun__) && defined(__svr4__))
 # error "This operating system is not supported"
 #endif
 
Index: lib/sanitizer_common/sanitizer_platform_interceptors.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -28,7 +28,7 @@
 # define SI_WINDOWS 1
 #endif
 
-#if (SI_POSIX != 0) == (SI_WINDOWS != 0) && !SANITIZER_FUCHSIA
+#if SI_WINDOWS && SI_POSIX
 # error "Windows is not POSIX!"
 #endif
 
Index: lib/sanitizer_common/sanitizer_stacktrace.h
===================================================================
--- lib/sanitizer_common/sanitizer_stacktrace.h
+++ lib/sanitizer_common/sanitizer_stacktrace.h
@@ -32,7 +32,7 @@
 // Fast unwind is the only option on Mac for now; we will need to
 // revisit this macro when slow unwind works on Mac, see
 // https://github.com/google/sanitizers/issues/137
-#if SANITIZER_MAC || SANITIZER_OPENBSD
+#if SANITIZER_MAC || SANITIZER_OPENBSD || SANITIZER_RTEMS
 # define SANITIZER_CAN_SLOW_UNWIND 0
 #else
 # define SANITIZER_CAN_SLOW_UNWIND 1
Index: lib/sanitizer_common/sanitizer_stacktrace_printer.cc
===================================================================
--- lib/sanitizer_common/sanitizer_stacktrace_printer.cc
+++ lib/sanitizer_common/sanitizer_stacktrace_printer.cc
@@ -17,8 +17,8 @@
 
 namespace __sanitizer {
 
-// sanitizer_symbolizer_fuchsia.cc implements these differently for Fuchsia.
-#if !SANITIZER_FUCHSIA
+// sanitizer_symbolizer_markup.cc implements these differently.
+#if !SANITIZER_SYMBOLIZER_MARKUP
 
 static const char *StripFunctionName(const char *function, const char *prefix) {
   if (!function) return nullptr;
@@ -228,7 +228,7 @@
   }
 }
 
-#endif  // !SANITIZER_FUCHSIA
+#endif  // !SANITIZER_SYMBOLIZER_MARKUP
 
 void RenderSourceLocation(InternalScopedString *buffer, const char *file,
                           int line, int column, bool vs_style,
Index: lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
@@ -26,8 +26,8 @@
   return symbolizer_;
 }
 
-// See sanitizer_symbolizer_fuchsia.cc.
-#if !SANITIZER_FUCHSIA
+// See sanitizer_symbolizer_markup.cc.
+#if !SANITIZER_SYMBOLIZER_MARKUP
 
 const char *ExtractToken(const char *str, const char *delims, char **result) {
   uptr prefix_len = internal_strcspn(str, delims);
@@ -489,6 +489,6 @@
   return true;
 }
 
-#endif  // !SANITIZER_FUCHSIA
+#endif  // !SANITIZER_SYMBOLIZER_MARKUP
 
 }  // namespace __sanitizer
Index: lib/sanitizer_common/sanitizer_symbolizer_report.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_report.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_report.cc
@@ -117,7 +117,7 @@
 #endif
 }
 
-#if !SANITIZER_FUCHSIA && !SANITIZER_GO
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_GO
 void StartReportDeadlySignal() {
   // Write the first message using fd=2, just in case.
   // It may actually fail to write in case stderr is closed.
Index: lib/ubsan/ubsan_platform.h
===================================================================
--- lib/ubsan/ubsan_platform.h
+++ lib/ubsan/ubsan_platform.h
@@ -17,7 +17,7 @@
 #if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__) ||        \
     defined(__NetBSD__) || defined(__OpenBSD__) || \
     (defined(__sun__) && defined(__svr4__)) || \
-    defined(_WIN32) || defined(__Fuchsia__)
+    defined(_WIN32) || defined(__Fuchsia__) || defined(__rtems__)
 # define CAN_SANITIZE_UB 1
 #else
 # define CAN_SANITIZE_UB 0