Index: compiler-rt/trunk/lib/esan/esan_interceptors.cpp
===================================================================
--- compiler-rt/trunk/lib/esan/esan_interceptors.cpp
+++ compiler-rt/trunk/lib/esan/esan_interceptors.cpp
@@ -373,6 +373,8 @@
 #endif
 
 #if SANITIZER_LINUX
+DECLARE_REAL(int, sigaction, int signum, const struct sigaction *act,
+             struct sigaction *oldact)
 INTERCEPTOR(int, sigaction, int signum, const struct sigaction *act,
             struct sigaction *oldact) {
   void *ctx;
@@ -382,6 +384,15 @@
   else
     return REAL(sigaction)(signum, act, oldact);
 }
+
+// This is required to properly use internal_sigaction.
+namespace __sanitizer {
+int real_sigaction(int signum, const void *act, void *oldact) {
+  return REAL(sigaction)(signum, (const struct sigaction *)act,
+                         (struct sigaction *)oldact);
+}
+} // namespace __sanitizer
+
 #define ESAN_MAYBE_INTERCEPT_SIGACTION INTERCEPT_FUNCTION(sigaction)
 #else
 #error Platform not supported
Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.h
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.h
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.h
@@ -78,6 +78,8 @@
 
 int my_pthread_attr_getstack(void *attr, void **addr, uptr *size);
 
+// A routine named real_sigaction() must be implemented by each sanitizer in
+// order for internal_sigaction() to bypass interceptors.
 int internal_sigaction(int signum, const void *act, void *oldact);
 void internal_sigfillset(__sanitizer_sigset_t *set);