static const char *output_directory = NULL;
 static int outdir_offset;
 
-static int reopen_stdout(struct commit *commit, struct rev_info *rev, int quiet)
+static int reopen_stdout(struct commit *commit, const char *subject,
+                        struct rev_info *rev, int quiet)
 {
        struct strbuf filename = STRBUF_INIT;
        int suffix_len = strlen(fmt_patch_suffix) + 1;
                        strbuf_addch(&filename, '/');
        }
 
-       get_patch_filename(commit, rev->nr, fmt_patch_suffix, &filename);
+       get_patch_filename(commit, subject, rev->nr, fmt_patch_suffix, &filename);
 
        if (!quiet)
                fprintf(realstdout, "%s\n", filename.buf + outdir_offset);
        const char *encoding = "UTF-8";
        struct diff_options opts;
        int need_8bit_cte = 0;
-       struct commit *commit = NULL;
        struct pretty_print_context pp = {0};
 
        if (rev->commit_format != CMIT_FMT_EMAIL)
 
        committer = git_committer_info(0);
 
-       if (!numbered_files) {
-               /*
-                * We fake a commit for the cover letter so we get the filename
-                * desired.
-                */
-               commit = xcalloc(1, sizeof(*commit));
-               commit->buffer = xmalloc(400);
-               snprintf(commit->buffer, 400,
-                       "tree 0000000000000000000000000000000000000000\n"
-                       "parent %s\n"
-                       "author %s\n"
-                       "committer %s\n\n"
-                       "cover letter\n",
-                       sha1_to_hex(head->object.sha1), committer, committer);
-       }
-
-       if (!use_stdout && reopen_stdout(commit, rev, quiet))
+       if (!use_stdout &&
+           reopen_stdout(NULL, numbered_files ? NULL : "cover-letter", rev, quiet))
                return;
 
-       if (commit) {
-
-               free(commit->buffer);
-               free(commit);
-       }
-
        log_write_email_headers(rev, head, &pp.subject, &pp.after_subject,
                                &need_8bit_cte);
 
                        gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
                }
 
-               if (!use_stdout && reopen_stdout(numbered_files ? NULL : commit,
-                                                &rev, quiet))
+               if (!use_stdout &&
+                   reopen_stdout(numbered_files ? NULL : commit, NULL, &rev, quiet))
                        die(_("Failed to create output files"));
                shown = log_tree_commit(&rev, commit);
                free(commit->buffer);
 
        return result;
 }
 
-void get_patch_filename(struct commit *commit, int nr, const char *suffix,
-                       struct strbuf *buf)
+void get_patch_filename(struct commit *commit, const char *subject, int nr,
+                       const char *suffix, struct strbuf *buf)
 {
        int suffix_len = strlen(suffix) + 1;
        int start_len = buf->len;
 
-       strbuf_addf(buf, commit ? "%04d-" : "%d", nr);
-       if (commit) {
+       strbuf_addf(buf, commit || subject ? "%04d-" : "%d", nr);
+       if (commit || subject) {
                int max_len = start_len + FORMAT_PATCH_NAME_MAX - suffix_len;
                struct pretty_print_context ctx = {0};
-               ctx.date_mode = DATE_NORMAL;
 
-               format_commit_message(commit, "%f", buf, &ctx);
+               if (subject)
+                       strbuf_addstr(buf, subject);
+               else if (commit)
+                       format_commit_message(commit, "%f", buf, &ctx);
+
                if (max_len < buf->len)
                        strbuf_setlen(buf, max_len);
                strbuf_addstr(buf, suffix);
                         mime_boundary_leader, opt->mime_boundary);
                extra_headers = subject_buffer;
 
-               get_patch_filename(opt->numbered_files ? NULL : commit, opt->nr,
-                                   opt->patch_suffix, &filename);
+               get_patch_filename(opt->numbered_files ? NULL : commit, NULL,
+                                  opt->nr, opt->patch_suffix, &filename);
                snprintf(buffer, sizeof(buffer) - 1,
                         "\n--%s%s\n"
                         "Content-Type: text/x-patch;"
 
 void load_ref_decorations(int flags);
 
 #define FORMAT_PATCH_NAME_MAX 64
-void get_patch_filename(struct commit *commit, int nr, const char *suffix,
-                       struct strbuf *buf);
+void get_patch_filename(struct commit *commit, const char *subject, int nr,
+                       const char *suffix, struct strbuf *buf);
 
 #endif