Index: lib/sanitizer_common/sanitizer_fuchsia.cc
===================================================================
--- lib/sanitizer_common/sanitizer_fuchsia.cc
+++ lib/sanitizer_common/sanitizer_fuchsia.cc
@@ -283,8 +283,14 @@
   else
     CHECK_EQ(addr + size, reinterpret_cast<uptr>(base_) + size_);
   size_ -= size;
-  UnmapOrDieVmar(reinterpret_cast<void *>(addr), size,
-                 static_cast<zx_handle_t>(os_handle_));
+  const zx_handle_t vmar = static_cast<zx_handle_t>(os_handle_);
+  UnmapOrDieVmar(reinterpret_cast<void *>(addr), size, vmar);
+  if (!base_) {
+    // If we unmapped the whole range, destroy and close the vmar.
+    _zx_vmar_destroy(vmar);
+    _zx_handle_close(vmar);
+    os_handle_ = static_cast<uptr>(ZX_HANDLE_INVALID);
+  }
 }
 
 // This should never be called.