diff --git a/compiler-rt/lib/hwasan/hwasan_interceptors.cpp b/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
--- a/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
@@ -197,16 +197,16 @@
   }
   void *res = real_mmap(addr, length, prot, flags, fd, offset);
   if (res != (void *)-1) {
-    void *end_res = (char *)res + (rounded_length - 1);
-    if (!MemIsApp(reinterpret_cast<uptr>(res)) ||
-        !MemIsApp(reinterpret_cast<uptr>(end_res))) {
+    uptr beg = reinterpret_cast<uptr>(res);
+    DCHECK(IsAligned(beg, GetPageSize()));
+    if (!MemIsApp(beg) || !MemIsApp(beg + rounded_length - 1)) {
       // Application has attempted to map more memory than is supported by
       // HWASan. Act as if we ran out of memory.
       internal_munmap(res, length);
       errno = errno_ENOMEM;
       return (void *)-1;
     }
-    __hwasan::TagMemory(reinterpret_cast<uptr>(addr), length, 0);
+    __hwasan::TagMemoryAligned(beg, rounded_length, 0);
   }
 
   return res;
@@ -214,7 +214,17 @@
 
 template <class Munmap>
 static int munmap_interceptor(Munmap real_munmap, void *addr, SIZE_T length) {
-  __hwasan::TagMemory(reinterpret_cast<uptr>(addr), length, 0);
+  // We should not tag if munmap fail, but it's to late to tag after
+  // real_munmap, as the pages could be mmaped by another thread.
+  uptr beg = reinterpret_cast<uptr>(addr);
+  SIZE_T rounded_length = RoundUpTo(length, GetPageSize());
+  // Protect from unmapping the shadow.
+  if (!IsAligned(beg, GetPageSize()) || !MemIsApp(beg) ||
+      !MemIsApp(beg + rounded_length - 1)) {
+    errno = errno_EINVAL;
+    return -1;
+  }
+  __hwasan::TagMemoryAligned(beg, rounded_length, 0);
   return real_munmap(addr, length);
 }
 
diff --git a/compiler-rt/test/hwasan/TestCases/munmap.c b/compiler-rt/test/hwasan/TestCases/munmap.c
--- a/compiler-rt/test/hwasan/TestCases/munmap.c
+++ b/compiler-rt/test/hwasan/TestCases/munmap.c
@@ -1,5 +1,6 @@
 // RUN: %clang_hwasan  %s -o %t
-// RUN: %run %t 2>&1
+// RUN: %run %t 1 2>&1
+// RUN: %run %t 2 2>&1
 
 // REQUIRES: pointer-tagging
 
@@ -7,9 +8,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/mman.h>
+#include <unistd.h>
 
 int main(int argc, char **argv) {
-  const int kSize = 4096;
+  const size_t kPS = sysconf(_SC_PAGESIZE);
+  const int kSize = kPS / atoi(argv[1]);
   const int kTag = 47;
 
   // Get any mmaped pointer.
@@ -27,26 +30,36 @@
   }
 
   // Manually tag the pointer and the memory.
-  __hwasan_tag_memory(r, kTag, kSize);
+  __hwasan_tag_memory(r, kTag, kPS);
   int *p1 = __hwasan_tag_pointer(r, kTag);
 
   // Check that the pointer and the tag match.
-  if (__hwasan_test_shadow(p1, kSize) != -1) {
+  if (__hwasan_test_shadow(p1, kPS) != -1) {
     fprintf(stderr, "Failed to tag.\n");
     abort();
   }
 
+  if (munmap((char *)r + 1, kSize) == 0) {
+    perror("munmap should fail: ");
+    abort();
+  }
+
+  if (__hwasan_test_shadow(p1, kPS) != -1) {
+    fprintf(stderr, "Still must be tagged.\n");
+    abort();
+  }
+
   // First munmmap and then mmap the same pointer using MAP_FIXED.
   if (munmap((char *)r, kSize) != 0) {
     perror("Failed to unmap: ");
     abort();
   }
 
-  if (__hwasan_test_shadow(r, kSize) != -1) {
+  if (__hwasan_test_shadow(r, kPS) != -1) {
     fprintf(stderr, "Shadow memory was not cleaned by munmap.\n");
     abort();
   }
-  __hwasan_tag_memory(r, kTag, kSize);
+  __hwasan_tag_memory(r, kTag, kPS);
   int *p2 = (int *)mmap(r, kSize, PROT_READ | PROT_WRITE,
                         MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
 
@@ -57,7 +70,7 @@
   }
 
   // Make sure we can access the shadow with an untagged pointer.
-  if (__hwasan_test_shadow(p2, kSize) != -1) {
+  if (__hwasan_test_shadow(p2, kPS) != -1) {
     fprintf(stderr, "Shadow memory was not cleaned by mmap.\n");
     abort();
   }