diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index 4e629655bf..867c19b5ea 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -84,6 +84,11 @@ config("debug") {
 config("release") {
   defines = [ "NDEBUG" ]
 
+  if (is_mac || is_ios) {
+    # Disable NSAsserts in release builds.
+    defines += [ "NS_BLOCK_ASSERTIONS=1" ]
+  }
+
   # Sanitizers.
   # TODO(GYP) The GYP build has "release_valgrind_build == 0" for this
   # condition. When Valgrind is set up, we need to do the same here.