diff --git a/compiler-rt/lib/dfsan/dfsan_interceptors.cpp b/compiler-rt/lib/dfsan/dfsan_interceptors.cpp
--- a/compiler-rt/lib/dfsan/dfsan_interceptors.cpp
+++ b/compiler-rt/lib/dfsan/dfsan_interceptors.cpp
@@ -22,6 +22,18 @@
 
 static bool interceptors_initialized;
 
+namespace {
+
+void ReleasseShadowMemoryPagesToOS(void *addr, SIZE_T length) {
+  uptr beg_shadow_addr = (uptr)__dfsan::shadow_for(addr);
+  void *end_addr =
+      (void *)((uptr)addr + RoundUpTo(length, GetPageSizeCached()));
+  uptr end_shadow_addr = (uptr)__dfsan::shadow_for(end_addr);
+  ReleaseMemoryPagesToOS(beg_shadow_addr, end_shadow_addr);
+}
+
+}  // namespace
+
 INTERCEPTOR(void *, mmap, void *addr, SIZE_T length, int prot, int flags,
             int fd, OFF_T offset) {
   void *res;
@@ -34,7 +46,7 @@
     res = REAL(mmap)(addr, length, prot, flags, fd, offset);
 
   if (res != (void *)-1)
-    dfsan_set_label(0, res, RoundUpTo(length, GetPageSize()));
+    ReleasseShadowMemoryPagesToOS(res, length);
   return res;
 }
 
@@ -42,18 +54,14 @@
             int fd, OFF64_T offset) {
   void *res = REAL(mmap64)(addr, length, prot, flags, fd, offset);
   if (res != (void *)-1)
-    dfsan_set_label(0, res, RoundUpTo(length, GetPageSize()));
+    ReleasseShadowMemoryPagesToOS(res, length);
   return res;
 }
 
 INTERCEPTOR(int, munmap, void *addr, SIZE_T length) {
   int res = REAL(munmap)(addr, length);
   if (res != -1) {
-    uptr beg_shadow_addr = (uptr)__dfsan::shadow_for(addr);
-    void *end_addr =
-        (void *)((uptr)addr + RoundUpTo(length, GetPageSizeCached()));
-    uptr end_shadow_addr = (uptr)__dfsan::shadow_for(end_addr);
-    ReleaseMemoryPagesToOS(beg_shadow_addr, end_shadow_addr);
+    ReleasseShadowMemoryPagesToOS(addr, length);
   }
   return res;
 }
diff --git a/compiler-rt/test/dfsan/mmap_release_shadow.c b/compiler-rt/test/dfsan/mmap_release_shadow.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/dfsan/mmap_release_shadow.c
@@ -0,0 +1,43 @@
+// RUN: %clang_dfsan %s -o %t && %run %t
+
+#include <assert.h>
+#include <sanitizer/dfsan_interface.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+size_t get_rss_kb() {
+  long rss = 0L;
+  FILE *f = NULL;
+  assert((f = fopen("/proc/self/statm", "r")));
+  assert(fscanf(f, "%*s%ld", &rss) == 1);
+  fclose(f);
+  return ((size_t)rss * (size_t)sysconf(_SC_PAGESIZE)) >> 10;
+}
+
+int main(int argc, char **argv) {
+  const size_t map_size = 100 << 20;
+  size_t before = get_rss_kb();
+
+  char *p = mmap(NULL, map_size, PROT_READ | PROT_WRITE,
+                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  memset(p, 0xff, map_size);
+  size_t after_mmap = get_rss_kb();
+
+  const dfsan_label label = dfsan_create_label("l", 0);
+  char val = 0xff;
+  dfsan_set_label(label, &val, sizeof(val));
+  memset(p, val, map_size);
+  size_t after_set_label = get_rss_kb();
+
+  fprintf(stderr, "RSS at start: %td, after mmap: %td, after set label: %td\n",
+          before, after_mmap, after_set_label);
+
+  const size_t mmap_cost_kb = map_size >> 10;
+  const size_t mmap_shadow_cost_kb = 2 * mmap_cost_kb;
+  assert(after_mmap >= before + mmap_cost_kb);
+  assert(after_set_label >= after_mmap + mmap_shadow_cost_kb);
+  return 0;
+}