diff --git a/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp b/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
@@ -855,9 +855,15 @@
 constexpr u32 kGuardRunning = 1 << 16;
 constexpr u32 kGuardWaiter = 1 << 17;
 
-static int guard_acquire(ThreadState *thr, uptr pc, atomic_uint32_t *g) {
-  OnPotentiallyBlockingRegionBegin();
-  auto on_exit = at_scope_exit(&OnPotentiallyBlockingRegionEnd);
+static int guard_acquire(ThreadState *thr, uptr pc, atomic_uint32_t *g,
+                         bool blocking_hooks = true) {
+  if (blocking_hooks)
+    OnPotentiallyBlockingRegionBegin();
+  auto on_exit = at_scope_exit([blocking_hooks] {
+    if (blocking_hooks)
+      OnPotentiallyBlockingRegionEnd();
+  });
+
   for (;;) {
     u32 cmp = atomic_load(g, memory_order_acquire);
     if (cmp == kGuardInit) {
@@ -1509,7 +1515,9 @@
   else
     a = static_cast<atomic_uint32_t*>(o);
 
-  if (guard_acquire(thr, pc, a)) {
+  // Mac OS X appears to use pthread_once() where calling BlockingRegion hooks
+  // result in crashes due to too little stack space.
+  if (guard_acquire(thr, pc, a, !SANITIZER_MAC)) {
     (*f)();
     guard_release(thr, pc, a);
   }