diff --git a/pretty.c b/pretty.c
index 85499347514ec3e1d62d6caa9f53b886c556e345..65d20a7a2e7cafd79ff95c02cab3303ebb72351c 100644
--- a/pretty.c
+++ b/pretty.c
@@ -216,36 +216,53 @@ static int is_rfc2047_special(char ch)
 static void add_rfc2047(struct strbuf *sb, const char *line, int len,
 		       const char *encoding)
 {
-	int i, last;
+	static const int max_length = 78; /* per rfc2822 */
+	int i;
+	int line_len;
+
+	/* How many bytes are already used on the current line? */
+	for (i = sb->len - 1; i >= 0; i--)
+		if (sb->buf[i] == '\n')
+			break;
+	line_len = sb->len - (i+1);
 
 	for (i = 0; i < len; i++) {
 		int ch = line[i];
-		if (non_ascii(ch))
+		if (non_ascii(ch) || ch == '\n')
 			goto needquote;
 		if ((i + 1 < len) && (ch == '=' && line[i+1] == '?'))
 			goto needquote;
 	}
-	strbuf_add(sb, line, len);
+	strbuf_add_wrapped_bytes(sb, line, len, 0, 1, max_length - line_len);
 	return;
 
 needquote:
 	strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
 	strbuf_addf(sb, "=?%s?q?", encoding);
-	for (i = last = 0; i < len; i++) {
+	line_len += strlen(encoding) + 5; /* 5 for =??q? */
+	for (i = 0; i < len; i++) {
 		unsigned ch = line[i] & 0xFF;
+
+		if (line_len >= max_length - 2) {
+			strbuf_addf(sb, "?=\n =?%s?q?", encoding);
+			line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
+		}
+
 		/*
 		 * We encode ' ' using '=20' even though rfc2047
 		 * allows using '_' for readability.  Unfortunately,
 		 * many programs do not understand this and just
 		 * leave the underscore in place.
 		 */
-		if (is_rfc2047_special(ch) || ch == ' ') {
-			strbuf_add(sb, line + last, i - last);
+		if (is_rfc2047_special(ch) || ch == ' ' || ch == '\n') {
 			strbuf_addf(sb, "=%02X", ch);
-			last = i + 1;
+			line_len += 3;
+		}
+		else {
+			strbuf_addch(sb, ch);
+			line_len++;
 		}
 	}
-	strbuf_add(sb, line + last, len - last);
 	strbuf_addstr(sb, "?=");
 }
 
@@ -1106,11 +1123,10 @@ void pp_title_line(enum cmit_fmt fmt,
 		   const char *encoding,
 		   int need_8bit_cte)
 {
-	const char *line_separator = (fmt == CMIT_FMT_EMAIL) ? "\n " : " ";
 	struct strbuf title;
 
 	strbuf_init(&title, 80);
-	*msg_p = format_subject(&title, *msg_p, line_separator);
+	*msg_p = format_subject(&title, *msg_p, " ");
 
 	strbuf_grow(sb, title.len + 1024);
 	if (subject) {
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 027c13d52cd701ba28e3c5e29c5431acfccdad73..9c663677df0887cc09ce2c8277ec300e8de4eaaa 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -709,4 +709,88 @@ test_expect_success TTY 'format-patch --stdout paginates' '
 	test_path_is_missing .git/pager_used
 '
 
+test_expect_success 'format-patch handles multi-line subjects' '
+	rm -rf patches/ &&
+	echo content >>file &&
+	for i in one two three; do echo $i; done >msg &&
+	git add file &&
+	git commit -F msg &&
+	git format-patch -o patches -1 &&
+	grep ^Subject: patches/0001-one.patch >actual &&
+	echo "Subject: [PATCH] one two three" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'format-patch handles multi-line encoded subjects' '
+	rm -rf patches/ &&
+	echo content >>file &&
+	for i in en två tre; do echo $i; done >msg &&
+	git add file &&
+	git commit -F msg &&
+	git format-patch -o patches -1 &&
+	grep ^Subject: patches/0001-en.patch >actual &&
+	echo "Subject: [PATCH] =?UTF-8?q?en=20tv=C3=A5=20tre?=" >expect &&
+	test_cmp expect actual
+'
+
+M8="foo bar "
+M64=$M8$M8$M8$M8$M8$M8$M8$M8
+M512=$M64$M64$M64$M64$M64$M64$M64$M64
+cat >expect <<'EOF'
+Subject: [PATCH] foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar
+EOF
+test_expect_success 'format-patch wraps extremely long headers (ascii)' '
+	echo content >>file &&
+	git add file &&
+	git commit -m "$M512" &&
+	git format-patch --stdout -1 >patch &&
+	sed -n "/^Subject/p; /^ /p; /^$/q" <patch >subject &&
+	test_cmp expect subject
+'
+
+M8="föö bar "
+M64=$M8$M8$M8$M8$M8$M8$M8$M8
+M512=$M64$M64$M64$M64$M64$M64$M64$M64
+cat >expect <<'EOF'
+Subject: [PATCH] =?UTF-8?q?f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?=
+EOF
+test_expect_success 'format-patch wraps extremely long headers (rfc2047)' '
+	rm -rf patches/ &&
+	echo content >>file &&
+	git add file &&
+	git commit -m "$M512" &&
+	git format-patch --stdout -1 >patch &&
+	sed -n "/^Subject/p; /^ /p; /^$/q" <patch >subject &&
+	test_cmp expect subject
+'
+
 test_done
diff --git a/utf8.c b/utf8.c
index 84cfc72e6db144880febad0a4ffa64800919fb6d..8acbc660d31a3552a4451749353139e0dcd371bd 100644
--- a/utf8.c
+++ b/utf8.c
@@ -405,6 +405,15 @@ int strbuf_add_wrapped_text(struct strbuf *buf,
 	}
 }
 
+int strbuf_add_wrapped_bytes(struct strbuf *buf, const char *data, int len,
+			     int indent, int indent2, int width)
+{
+	char *tmp = xstrndup(data, len);
+	int r = strbuf_add_wrapped_text(buf, tmp, indent, indent2, width);
+	free(tmp);
+	return r;
+}
+
 int is_encoding_utf8(const char *name)
 {
 	if (!name)
diff --git a/utf8.h b/utf8.h
index ebc4d2fa85113c971ab4c4eaa52537a688a03745..81f2c82fabcf63e3bb02c15beb4a0409afd9ab7b 100644
--- a/utf8.h
+++ b/utf8.h
@@ -10,6 +10,8 @@ int is_encoding_utf8(const char *name);
 
 int strbuf_add_wrapped_text(struct strbuf *buf,
 		const char *text, int indent, int indent2, int width);
+int strbuf_add_wrapped_bytes(struct strbuf *buf, const char *data, int len,
+			     int indent, int indent2, int width);
 
 #ifndef NO_ICONV
 char *reencode_string(const char *in, const char *out_encoding, const char *in_encoding);