diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
@@ -999,7 +999,6 @@
     // Reset middle part.
     u64 *p1 = p;
     p = RoundDown(end, kPageSize);
-    UnmapOrDie((void*)p1, (uptr)p - (uptr)p1);
     if (!MmapFixedSuperNoReserve((uptr)p1, (uptr)p - (uptr)p1))
       Die();
     // Set the ending.
diff --git a/compiler-rt/test/tsan/mmap_stress2.cpp b/compiler-rt/test/tsan/mmap_stress2.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/tsan/mmap_stress2.cpp
@@ -0,0 +1,51 @@
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=report_atomic_races=0 %run %t 2>&1 | FileCheck %s
+// This test exposed non-atomicity in mmap interceptor
+// which made shadow for the region temporarily unmapped.
+// This resulted in crashes in the Accesser thread.
+#include "test.h"
+#include <errno.h>
+#include <sys/mman.h>
+
+// The size needs to be large enough to trigger
+// large region optimization in the runtime.
+const size_t kMmapSize = 16 << 20;
+
+void *Remapper(void *arg) {
+  for (;;) {
+    void *p = mmap(arg, kMmapSize, PROT_READ | PROT_WRITE,
+                   MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0);
+    if (p == MAP_FAILED)
+      exit(printf("mmap failed: %d\n", errno));
+  }
+  return 0;
+}
+
+void *Accesser(void *arg) {
+  unsigned rnd = time(0);
+  for (;;) {
+    int index = rand_r(&rnd) % kMmapSize;
+    char *p = &((char *)arg)[index];
+    __atomic_fetch_add(p, 1, __ATOMIC_ACQ_REL);
+  }
+  return 0;
+}
+
+int main() {
+  void *p = mmap(0, kMmapSize, PROT_READ | PROT_WRITE,
+                 MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (p == MAP_FAILED)
+    exit(printf("mmap failed: %d\n", errno));
+  pthread_attr_t attr;
+  pthread_attr_init(&attr);
+  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+  pthread_t th[2];
+  if (pthread_create(&th[0], &attr, Remapper, p))
+    exit(printf("pthread_create failed: %d\n", errno));
+  if (pthread_create(&th[1], &attr, Accesser, p))
+    exit(printf("pthread_create failed: %d\n", errno));
+  pthread_attr_destroy(&attr);
+  sleep(3);
+  fprintf(stderr, "DONE\n");
+}
+
+// CHECK: DONE