#endif
 #endif
 
+static int builtin_grep;
+
 /*
  * git grep pathspecs are somewhat different from diff-tree pathspecs;
  * pathname wildcards are allowed.
                push_arg("-E");
        if (opt->regflags & REG_ICASE)
                push_arg("-i");
+       if (opt->binary == GREP_BINARY_NOMATCH)
+               push_arg("-I");
        if (opt->word_regexp)
                push_arg("-w");
        if (opt->name_only)
         * we grep through the checked-out files. It tends to
         * be a lot more optimized
         */
-       if (!cached) {
+       if (!cached && !builtin_grep) {
                hit = external_grep(opt, paths, cached);
                if (hit >= 0)
                        return hit;
                        continue;
                if (!pathspec_matches(paths, ce->name))
                        continue;
-               if (cached) {
+               /*
+                * If CE_VALID is on, we assume worktree file and its cache entry
+                * are identical, even if worktree file has been modified, so use
+                * cache version instead
+                */
+               if (cached || (ce->ce_flags & CE_VALID)) {
                        if (ce_stage(ce))
                                continue;
                        hit |= grep_sha1(opt, ce->sha1, ce->name, 0);
                        cached = 1;
                        continue;
                }
+               if (!strcmp("--no-ext-grep", arg)) {
+                       builtin_grep = 1;
+                       continue;
+               }
                if (!strcmp("-a", arg) ||
                    !strcmp("--text", arg)) {
                        opt.binary = GREP_BINARY_TEXT;