diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -4032,7 +4032,7 @@
   // FIXME: under ASan the call below may write to freed memory and corrupt
   // its metadata. See
   // https://github.com/google/sanitizers/issues/321.
-  int res = REAL(sigwait)(set, sig);
+  int res = COMMON_INTERCEPTOR_BLOCK_REAL(sigwait)(set, sig);
   if (!res && sig) COMMON_INTERCEPTOR_WRITE_RANGE(ctx, sig, sizeof(*sig));
   return res;
 }
@@ -4049,7 +4049,7 @@
   // FIXME: under ASan the call below may write to freed memory and corrupt
   // its metadata. See
   // https://github.com/google/sanitizers/issues/321.
-  int res = REAL(sigwaitinfo)(set, info);
+  int res = COMMON_INTERCEPTOR_BLOCK_REAL(sigwaitinfo)(set, info);
   if (res > 0 && info) COMMON_INTERCEPTOR_WRITE_RANGE(ctx, info, siginfo_t_sz);
   return res;
 }
@@ -4068,7 +4068,7 @@
   // FIXME: under ASan the call below may write to freed memory and corrupt
   // its metadata. See
   // https://github.com/google/sanitizers/issues/321.
-  int res = REAL(sigtimedwait)(set, info, timeout);
+  int res = COMMON_INTERCEPTOR_BLOCK_REAL(sigtimedwait)(set, info, timeout);
   if (res > 0 && info) COMMON_INTERCEPTOR_WRITE_RANGE(ctx, info, siginfo_t_sz);
   return res;
 }
diff --git a/compiler-rt/test/tsan/signal_block2.cpp b/compiler-rt/test/tsan/signal_block2.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/tsan/signal_block2.cpp
@@ -0,0 +1,91 @@
+// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+// The test was reported to hang sometimes on Darwin:
+// https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20210517/917003.html
+// UNSUPPORTED: darwin
+
+#include "test.h"
+#include <signal.h>
+#include <string.h>
+#include <sys/time.h>
+
+int test;
+int done;
+int signals_handled;
+pthread_t main_thread;
+pthread_mutex_t mutex;
+pthread_cond_t cond;
+
+void timer_handler(int signum) {
+  write(2, "timer_handler\n", strlen("timer_handler\n"));
+  if (++signals_handled < 10)
+    return;
+  switch (test) {
+  case 0:
+    __atomic_store_n(&done, 1, __ATOMIC_RELEASE);
+    (void)pthread_kill(main_thread, SIGUSR1);
+  case 1:
+    if (pthread_mutex_trylock(&mutex) == 0) {
+      __atomic_store_n(&done, 1, __ATOMIC_RELEASE);
+      pthread_cond_signal(&cond);
+      pthread_mutex_unlock(&mutex);
+    }
+  case 2:
+    __atomic_store_n(&done, 1, __ATOMIC_RELEASE);
+  }
+}
+
+int main(int argc, char **argv) {
+  main_thread = pthread_self();
+  pthread_mutex_init(&mutex, 0);
+  pthread_cond_init(&cond, 0);
+
+  sigset_t sigset;
+  sigemptyset(&sigset);
+  sigaddset(&sigset, SIGUSR1);
+  if (sigprocmask(SIG_BLOCK, &sigset, NULL))
+    exit((perror("sigprocmask"), 1));
+
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = &timer_handler;
+  if (sigaction(SIGALRM, &sa, NULL))
+    exit((perror("setitimer"), 1));
+
+  for (test = 0; test < 3; test++) {
+    fprintf(stderr, "test %d\n", test);
+    struct itimerval timer;
+    timer.it_value.tv_sec = 0;
+    timer.it_value.tv_usec = 50000;
+    timer.it_interval = timer.it_value;
+    if (setitimer(ITIMER_REAL, &timer, NULL))
+      exit((perror("setitimer"), 1));
+
+    switch (test) {
+    case 0:
+      while (__atomic_load_n(&done, __ATOMIC_ACQUIRE) == 0) {
+        int signum;
+        sigwait(&sigset, &signum);
+        write(2, "sigwait\n", strlen("sigwait\n"));
+      }
+    case 1:
+      pthread_mutex_lock(&mutex);
+      while (__atomic_load_n(&done, __ATOMIC_ACQUIRE) == 0) {
+        pthread_cond_wait(&cond, &mutex);
+        write(2, "pthread_cond_wait\n", strlen("pthread_cond_wait\n"));
+      }
+      pthread_mutex_unlock(&mutex);
+    case 2:
+      while (__atomic_load_n(&done, __ATOMIC_ACQUIRE) == 0) {
+      }
+    }
+
+    memset(&timer, 0, sizeof(timer));
+    if (setitimer(ITIMER_REAL, &timer, NULL))
+      exit((perror("setitimer"), 1));
+    done = 0;
+    signals_handled = 0;
+  }
+  fprintf(stderr, "DONE\n");
+}
+
+// CHECK: DONE