diff --git a/builtin/am.c b/builtin/am.c
index 33d1f24d07bf12a350dc1e0c4eba952ba226400a..d82d07edaab317faa751c2b4c36f91d66d9622b9 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -65,9 +65,22 @@ static int linelen(const char *msg)
 	return strchrnul(msg, '\n') - msg;
 }
 
+/**
+ * Returns true if `str` consists of only whitespace, false otherwise.
+ */
+static int str_isspace(const char *str)
+{
+	for (; *str; str++)
+		if (!isspace(*str))
+			return 0;
+
+	return 1;
+}
+
 enum patch_format {
 	PATCH_FORMAT_UNKNOWN = 0,
-	PATCH_FORMAT_MBOX
+	PATCH_FORMAT_MBOX,
+	PATCH_FORMAT_STGIT
 };
 
 enum keep_type {
@@ -610,6 +623,8 @@ static int detect_patch_format(const char **paths)
 {
 	enum patch_format ret = PATCH_FORMAT_UNKNOWN;
 	struct strbuf l1 = STRBUF_INIT;
+	struct strbuf l2 = STRBUF_INIT;
+	struct strbuf l3 = STRBUF_INIT;
 	FILE *fp;
 
 	/*
@@ -635,6 +650,23 @@ static int detect_patch_format(const char **paths)
 		goto done;
 	}
 
+	strbuf_reset(&l2);
+	strbuf_getline_crlf(&l2, fp);
+	strbuf_reset(&l3);
+	strbuf_getline_crlf(&l3, fp);
+
+	/*
+	 * If the second line is empty and the third is a From, Author or Date
+	 * entry, this is likely an StGit patch.
+	 */
+	if (l1.len && !l2.len &&
+		(starts_with(l3.buf, "From:") ||
+		 starts_with(l3.buf, "Author:") ||
+		 starts_with(l3.buf, "Date:"))) {
+		ret = PATCH_FORMAT_STGIT;
+		goto done;
+	}
+
 	if (l1.len && is_mail(fp)) {
 		ret = PATCH_FORMAT_MBOX;
 		goto done;
@@ -674,6 +706,100 @@ static int split_mail_mbox(struct am_state *state, const char **paths, int keep_
 	return 0;
 }
 
+/**
+ * Callback signature for split_mail_conv(). The foreign patch should be
+ * read from `in`, and the converted patch (in RFC2822 mail format) should be
+ * written to `out`. Return 0 on success, or -1 on failure.
+ */
+typedef int (*mail_conv_fn)(FILE *out, FILE *in, int keep_cr);
+
+/**
+ * Calls `fn` for each file in `paths` to convert the foreign patch to the
+ * RFC2822 mail format suitable for parsing with git-mailinfo.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail_conv(mail_conv_fn fn, struct am_state *state,
+			const char **paths, int keep_cr)
+{
+	static const char *stdin_only[] = {"-", NULL};
+	int i;
+
+	if (!*paths)
+		paths = stdin_only;
+
+	for (i = 0; *paths; paths++, i++) {
+		FILE *in, *out;
+		const char *mail;
+		int ret;
+
+		if (!strcmp(*paths, "-"))
+			in = stdin;
+		else
+			in = fopen(*paths, "r");
+
+		if (!in)
+			return error(_("could not open '%s' for reading: %s"),
+					*paths, strerror(errno));
+
+		mail = mkpath("%s/%0*d", state->dir, state->prec, i + 1);
+
+		out = fopen(mail, "w");
+		if (!out)
+			return error(_("could not open '%s' for writing: %s"),
+					mail, strerror(errno));
+
+		ret = fn(out, in, keep_cr);
+
+		fclose(out);
+		fclose(in);
+
+		if (ret)
+			return error(_("could not parse patch '%s'"), *paths);
+	}
+
+	state->cur = 1;
+	state->last = i;
+	return 0;
+}
+
+/**
+ * A split_mail_conv() callback that converts an StGit patch to an RFC2822
+ * message suitable for parsing with git-mailinfo.
+ */
+static int stgit_patch_to_mail(FILE *out, FILE *in, int keep_cr)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int subject_printed = 0;
+
+	while (!strbuf_getline(&sb, in, '\n')) {
+		const char *str;
+
+		if (str_isspace(sb.buf))
+			continue;
+		else if (skip_prefix(sb.buf, "Author:", &str))
+			fprintf(out, "From:%s\n", str);
+		else if (starts_with(sb.buf, "From") || starts_with(sb.buf, "Date"))
+			fprintf(out, "%s\n", sb.buf);
+		else if (!subject_printed) {
+			fprintf(out, "Subject: %s\n", sb.buf);
+			subject_printed = 1;
+		} else {
+			fprintf(out, "\n%s\n", sb.buf);
+			break;
+		}
+	}
+
+	strbuf_reset(&sb);
+	while (strbuf_fread(&sb, 8192, in) > 0) {
+		fwrite(sb.buf, 1, sb.len, out);
+		strbuf_reset(&sb);
+	}
+
+	strbuf_release(&sb);
+	return 0;
+}
+
 /**
  * Splits a list of files/directories into individual email patches. Each path
  * in `paths` must be a file/directory that is formatted according to
@@ -702,6 +828,8 @@ static int split_mail(struct am_state *state, enum patch_format patch_format,
 	switch (patch_format) {
 	case PATCH_FORMAT_MBOX:
 		return split_mail_mbox(state, paths, keep_cr);
+	case PATCH_FORMAT_STGIT:
+		return split_mail_conv(stgit_patch_to_mail, state, paths, keep_cr);
 	default:
 		die("BUG: invalid patch_format");
 	}
@@ -1750,6 +1878,8 @@ static int parse_opt_patchformat(const struct option *opt, const char *arg, int
 
 	if (!strcmp(arg, "mbox"))
 		*opt_value = PATCH_FORMAT_MBOX;
+	else if (!strcmp(arg, "stgit"))
+		*opt_value = PATCH_FORMAT_STGIT;
 	else
 		return error(_("Invalid value for --patch-format: %s"), arg);
 	return 0;