diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
@@ -880,6 +880,9 @@
 #if defined(__x86_64__) || defined(__i386__)
   ucontext_t *ucontext = static_cast<ucontext_t*>(context);
   return ucontext->uc_mcontext->__es.__err & 2 /*T_PF_WRITE*/ ? Write : Read;
+#elif defined(__arm64__)
+  ucontext_t *ucontext = static_cast<ucontext_t*>(context);
+  return ucontext->uc_mcontext->__es.__esr & 0x40 /*ESR WnR*/ ? Write : Read;
 #else
   return Unknown;
 #endif