diff --git a/Documentation/config.txt b/Documentation/config.txt
index ef45c99e53..5ecb0fccb1 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1525,6 +1525,10 @@ log.showroot::
 	Tools like linkgit:git-log[1] or linkgit:git-whatchanged[1], which
 	normally hide the root commit will now show it. True by default.
 
+log.mailmap::
+	If true, makes linkgit:git-log[1], linkgit:git-show[1], and
+	linkgit:git-whatchanged[1] assume `--use-mailmap`.
+
 mailmap.file::
 	The location of an augmenting mailmap file. The default
 	mailmap, located in the root of the repository, is loaded
diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 08a185db7f..22c0d6e4b1 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -47,6 +47,11 @@ OPTIONS
 	Print out the ref name given on the command line by which each
 	commit was reached.
 
+--use-mailmap::
+	Use mailmap file to map author and committer names and email
+	to canonical real names and email addresses. See
+	linkgit:git-shortlog[1].
+
 --full-diff::
 	Without this flag, "git log -p <path>..." shows commits that
 	touch the specified paths, and diffs about the same specified
diff --git a/builtin/blame.c b/builtin/blame.c
index bc6c899d30..b431ba3209 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1322,30 +1322,31 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
  * Information on commits, used for output.
  */
 struct commit_info {
-	const char *author;
-	const char *author_mail;
+	struct strbuf author;
+	struct strbuf author_mail;
 	unsigned long author_time;
-	const char *author_tz;
+	struct strbuf author_tz;
 
 	/* filled only when asked for details */
-	const char *committer;
-	const char *committer_mail;
+	struct strbuf committer;
+	struct strbuf committer_mail;
 	unsigned long committer_time;
-	const char *committer_tz;
+	struct strbuf committer_tz;
 
-	const char *summary;
+	struct strbuf summary;
 };
 
 /*
  * Parse author/committer line in the commit object buffer
  */
 static void get_ac_line(const char *inbuf, const char *what,
-			int person_len, char *person,
-			int mail_len, char *mail,
-			unsigned long *time, const char **tz)
+	struct strbuf *name, struct strbuf *mail,
+	unsigned long *time, struct strbuf *tz)
 {
-	int len, tzlen, maillen;
-	char *tmp, *endp, *timepos, *mailpos;
+	struct ident_split ident;
+	size_t len, maillen, namelen;
+	char *tmp, *endp;
+	const char *namebuf, *mailbuf;
 
 	tmp = strstr(inbuf, what);
 	if (!tmp)
@@ -1356,69 +1357,61 @@ static void get_ac_line(const char *inbuf, const char *what,
 		len = strlen(tmp);
 	else
 		len = endp - tmp;
-	if (person_len <= len) {
+
+	if (split_ident_line(&ident, tmp, len)) {
 	error_out:
 		/* Ugh */
-		*tz = "(unknown)";
-		strcpy(person, *tz);
-		strcpy(mail, *tz);
+		tmp = "(unknown)";
+		strbuf_addstr(name, tmp);
+		strbuf_addstr(mail, tmp);
+		strbuf_addstr(tz, tmp);
 		*time = 0;
 		return;
 	}
-	memcpy(person, tmp, len);
 
-	tmp = person;
-	tmp += len;
-	*tmp = 0;
-	while (person < tmp && *tmp != ' ')
-		tmp--;
-	if (tmp <= person)
-		goto error_out;
-	*tz = tmp+1;
-	tzlen = (person+len)-(tmp+1);
+	namelen = ident.name_end - ident.name_begin;
+	namebuf = ident.name_begin;
 
-	*tmp = 0;
-	while (person < tmp && *tmp != ' ')
-		tmp--;
-	if (tmp <= person)
-		goto error_out;
-	*time = strtoul(tmp, NULL, 10);
-	timepos = tmp;
+	maillen = ident.mail_end - ident.mail_begin;
+	mailbuf = ident.mail_begin;
 
-	*tmp = 0;
-	while (person < tmp && !(*tmp == ' ' && tmp[1] == '<'))
-		tmp--;
-	if (tmp <= person)
-		return;
-	mailpos = tmp + 1;
-	*tmp = 0;
-	maillen = timepos - tmp;
-	memcpy(mail, mailpos, maillen);
+	*time = strtoul(ident.date_begin, NULL, 10);
 
-	if (!mailmap.nr)
-		return;
-
-	/*
-	 * mailmap expansion may make the name longer.
-	 * make room by pushing stuff down.
-	 */
-	tmp = person + person_len - (tzlen + 1);
-	memmove(tmp, *tz, tzlen);
-	tmp[tzlen] = 0;
-	*tz = tmp;
+	len = ident.tz_end - ident.tz_begin;
+	strbuf_add(tz, ident.tz_begin, len);
 
 	/*
 	 * Now, convert both name and e-mail using mailmap
 	 */
-	if (map_user(&mailmap, mail+1, mail_len-1, person, tmp-person-1)) {
-		/* Add a trailing '>' to email, since map_user returns plain emails
-		   Note: It already has '<', since we replace from mail+1 */
-		mailpos = memchr(mail, '\0', mail_len);
-		if (mailpos && mailpos-mail < mail_len - 1) {
-			*mailpos = '>';
-			*(mailpos+1) = '\0';
-		}
-	}
+	map_user(&mailmap, &mailbuf, &maillen,
+		 &namebuf, &namelen);
+
+	strbuf_addf(mail, "<%.*s>", (int)maillen, mailbuf);
+	strbuf_add(name, namebuf, namelen);
+}
+
+static void commit_info_init(struct commit_info *ci)
+{
+
+	strbuf_init(&ci->author, 0);
+	strbuf_init(&ci->author_mail, 0);
+	strbuf_init(&ci->author_tz, 0);
+	strbuf_init(&ci->committer, 0);
+	strbuf_init(&ci->committer_mail, 0);
+	strbuf_init(&ci->committer_tz, 0);
+	strbuf_init(&ci->summary, 0);
+}
+
+static void commit_info_destroy(struct commit_info *ci)
+{
+
+	strbuf_release(&ci->author);
+	strbuf_release(&ci->author_mail);
+	strbuf_release(&ci->author_tz);
+	strbuf_release(&ci->committer);
+	strbuf_release(&ci->committer_mail);
+	strbuf_release(&ci->committer_tz);
+	strbuf_release(&ci->summary);
 }
 
 static void get_commit_info(struct commit *commit,
@@ -1428,11 +1421,8 @@ static void get_commit_info(struct commit *commit,
 	int len;
 	const char *subject, *encoding;
 	char *reencoded, *message;
-	static char author_name[1024];
-	static char author_mail[1024];
-	static char committer_name[1024];
-	static char committer_mail[1024];
-	static char summary_buf[1024];
+
+	commit_info_init(ret);
 
 	/*
 	 * We've operated without save_commit_buffer, so
@@ -1450,11 +1440,8 @@ static void get_commit_info(struct commit *commit,
 	encoding = get_log_output_encoding();
 	reencoded = logmsg_reencode(commit, encoding);
 	message   = reencoded ? reencoded : commit->buffer;
-	ret->author = author_name;
-	ret->author_mail = author_mail;
 	get_ac_line(message, "\nauthor ",
-		    sizeof(author_name), author_name,
-		    sizeof(author_mail), author_mail,
+		    &ret->author, &ret->author_mail,
 		    &ret->author_time, &ret->author_tz);
 
 	if (!detailed) {
@@ -1462,21 +1449,16 @@ static void get_commit_info(struct commit *commit,
 		return;
 	}
 
-	ret->committer = committer_name;
-	ret->committer_mail = committer_mail;
 	get_ac_line(message, "\ncommitter ",
-		    sizeof(committer_name), committer_name,
-		    sizeof(committer_mail), committer_mail,
+		    &ret->committer, &ret->committer_mail,
 		    &ret->committer_time, &ret->committer_tz);
 
-	ret->summary = summary_buf;
 	len = find_commit_subject(message, &subject);
-	if (len && len < sizeof(summary_buf)) {
-		memcpy(summary_buf, subject, len);
-		summary_buf[len] = 0;
-	} else {
-		sprintf(summary_buf, "(%s)", sha1_to_hex(commit->object.sha1));
-	}
+	if (len)
+		strbuf_add(&ret->summary, subject, len);
+	else
+		strbuf_addf(&ret->summary, "(%s)", sha1_to_hex(commit->object.sha1));
+
 	free(reencoded);
 }
 
@@ -1505,15 +1487,15 @@ static int emit_one_suspect_detail(struct origin *suspect, int repeat)
 
 	suspect->commit->object.flags |= METAINFO_SHOWN;
 	get_commit_info(suspect->commit, &ci, 1);
-	printf("author %s\n", ci.author);
-	printf("author-mail %s\n", ci.author_mail);
+	printf("author %s\n", ci.author.buf);
+	printf("author-mail %s\n", ci.author_mail.buf);
 	printf("author-time %lu\n", ci.author_time);
-	printf("author-tz %s\n", ci.author_tz);
-	printf("committer %s\n", ci.committer);
-	printf("committer-mail %s\n", ci.committer_mail);
+	printf("author-tz %s\n", ci.author_tz.buf);
+	printf("committer %s\n", ci.committer.buf);
+	printf("committer-mail %s\n", ci.committer_mail.buf);
 	printf("committer-time %lu\n", ci.committer_time);
-	printf("committer-tz %s\n", ci.committer_tz);
-	printf("summary %s\n", ci.summary);
+	printf("committer-tz %s\n", ci.committer_tz.buf);
+	printf("summary %s\n", ci.summary.buf);
 	if (suspect->commit->object.flags & UNINTERESTING)
 		printf("boundary\n");
 	if (suspect->previous) {
@@ -1521,6 +1503,9 @@ static int emit_one_suspect_detail(struct origin *suspect, int repeat)
 		printf("previous %s ", sha1_to_hex(prev->commit->object.sha1));
 		write_name_quoted(prev->path, stdout, '\n');
 	}
+
+	commit_info_destroy(&ci);
+
 	return 1;
 }
 
@@ -1707,11 +1692,11 @@ static void emit_other(struct scoreboard *sb, struct blame_entry *ent, int opt)
 		if (opt & OUTPUT_ANNOTATE_COMPAT) {
 			const char *name;
 			if (opt & OUTPUT_SHOW_EMAIL)
-				name = ci.author_mail;
+				name = ci.author_mail.buf;
 			else
-				name = ci.author;
+				name = ci.author.buf;
 			printf("\t(%10s\t%10s\t%d)", name,
-			       format_time(ci.author_time, ci.author_tz,
+			       format_time(ci.author_time, ci.author_tz.buf,
 					   show_raw_time),
 			       ent->lno + 1 + cnt);
 		} else {
@@ -1730,14 +1715,14 @@ static void emit_other(struct scoreboard *sb, struct blame_entry *ent, int opt)
 				const char *name;
 				int pad;
 				if (opt & OUTPUT_SHOW_EMAIL)
-					name = ci.author_mail;
+					name = ci.author_mail.buf;
 				else
-					name = ci.author;
+					name = ci.author.buf;
 				pad = longest_author - utf8_strwidth(name);
 				printf(" (%s%*s %10s",
 				       name, pad, "",
 				       format_time(ci.author_time,
-						   ci.author_tz,
+						   ci.author_tz.buf,
 						   show_raw_time));
 			}
 			printf(" %*d) ",
@@ -1752,6 +1737,8 @@ static void emit_other(struct scoreboard *sb, struct blame_entry *ent, int opt)
 
 	if (sb->final_buf_size && cp[-1] != '\n')
 		putchar('\n');
+
+	commit_info_destroy(&ci);
 }
 
 static void output(struct scoreboard *sb, int option)
@@ -1876,9 +1863,9 @@ static void find_alignment(struct scoreboard *sb, int *option)
 			suspect->commit->object.flags |= METAINFO_SHOWN;
 			get_commit_info(suspect->commit, &ci, 1);
 			if (*option & OUTPUT_SHOW_EMAIL)
-				num = utf8_strwidth(ci.author_mail);
+				num = utf8_strwidth(ci.author_mail.buf);
 			else
-				num = utf8_strwidth(ci.author);
+				num = utf8_strwidth(ci.author.buf);
 			if (longest_author < num)
 				longest_author = num;
 		}
@@ -1890,6 +1877,8 @@ static void find_alignment(struct scoreboard *sb, int *option)
 			longest_dst_lines = num;
 		if (largest_score < ent_score(sb, e))
 			largest_score = ent_score(sb, e);
+
+		commit_info_destroy(&ci);
 	}
 	max_orig_digits = decimal_width(longest_src_lines);
 	max_digits = decimal_width(longest_dst_lines);
diff --git a/builtin/log.c b/builtin/log.c
index 5a4055eb0b..8f0b2e84fe 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -22,6 +22,7 @@
 #include "branch.h"
 #include "streaming.h"
 #include "version.h"
+#include "mailmap.h"
 
 /* Set a default date-time format for git log ("log.date" config variable) */
 static const char *default_date_mode = NULL;
@@ -30,6 +31,7 @@ static int default_abbrev_commit;
 static int default_show_root = 1;
 static int decoration_style;
 static int decoration_given;
+static int use_mailmap_config;
 static const char *fmt_patch_subject_prefix = "PATCH";
 static const char *fmt_pretty;
 
@@ -94,16 +96,18 @@ static void cmd_log_init_finish(int argc, const char **argv, const char *prefix,
 			 struct rev_info *rev, struct setup_revision_opt *opt)
 {
 	struct userformat_want w;
-	int quiet = 0, source = 0;
+	int quiet = 0, source = 0, mailmap = 0;
 
 	const struct option builtin_log_options[] = {
 		OPT_BOOLEAN(0, "quiet", &quiet, N_("suppress diff output")),
 		OPT_BOOLEAN(0, "source", &source, N_("show source")),
+		OPT_BOOLEAN(0, "use-mailmap", &mailmap, N_("Use mail map file")),
 		{ OPTION_CALLBACK, 0, "decorate", NULL, NULL, N_("decorate options"),
 		  PARSE_OPT_OPTARG, decorate_callback},
 		OPT_END()
 	};
 
+	mailmap = use_mailmap_config;
 	argc = parse_options(argc, argv, prefix,
 			     builtin_log_options, builtin_log_usage,
 			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN |
@@ -136,6 +140,11 @@ static void cmd_log_init_finish(int argc, const char **argv, const char *prefix,
 	if (source)
 		rev->show_source = 1;
 
+	if (mailmap) {
+		rev->mailmap = xcalloc(1, sizeof(struct string_list));
+		read_mailmap(rev->mailmap, NULL);
+	}
+
 	if (rev->pretty_given && rev->commit_format == CMIT_FMT_RAW) {
 		/*
 		 * "log --pretty=raw" is special; ignore UI oriented
@@ -351,6 +360,11 @@ static int git_log_config(const char *var, const char *value, void *cb)
 	}
 	if (!prefixcmp(var, "color.decorate."))
 		return parse_decorate_color_config(var, 15, value);
+	if (!strcmp(var, "log.mailmap")) {
+		use_mailmap_config = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (grep_config(var, value, cb) < 0)
 		return -1;
 	return git_diff_ui_config(var, value, cb);
diff --git a/builtin/shortlog.c b/builtin/shortlog.c
index 83605143ac..240bff3efa 100644
--- a/builtin/shortlog.c
+++ b/builtin/shortlog.c
@@ -36,52 +36,28 @@ static void insert_one_record(struct shortlog *log,
 	const char *dot3 = log->common_repo_prefix;
 	char *buffer, *p;
 	struct string_list_item *item;
-	char namebuf[1024];
-	char emailbuf[1024];
-	size_t len;
+	const char *mailbuf, *namebuf;
+	size_t namelen, maillen;
 	const char *eol;
-	const char *boemail, *eoemail;
 	struct strbuf subject = STRBUF_INIT;
+	struct strbuf namemailbuf = STRBUF_INIT;
+	struct ident_split ident;
 
-	boemail = strchr(author, '<');
-	if (!boemail)
-		return;
-	eoemail = strchr(boemail, '>');
-	if (!eoemail)
+	if (split_ident_line(&ident, author, strlen(author)))
 		return;
 
-	/* copy author name to namebuf, to support matching on both name and email */
-	memcpy(namebuf, author, boemail - author);
-	len = boemail - author;
-	while (len > 0 && isspace(namebuf[len-1]))
-		len--;
-	namebuf[len] = 0;
+	namebuf = ident.name_begin;
+	mailbuf = ident.mail_begin;
+	namelen = ident.name_end - ident.name_begin;
+	maillen = ident.mail_end - ident.mail_begin;
 
-	/* copy email name to emailbuf, to allow email replacement as well */
-	memcpy(emailbuf, boemail+1, eoemail - boemail);
-	emailbuf[eoemail - boemail - 1] = 0;
+	map_user(&log->mailmap, &mailbuf, &maillen, &namebuf, &namelen);
+	strbuf_add(&namemailbuf, namebuf, namelen);
 
-	if (!map_user(&log->mailmap, emailbuf, sizeof(emailbuf), namebuf, sizeof(namebuf))) {
-		while (author < boemail && isspace(*author))
-			author++;
-		for (len = 0;
-		     len < sizeof(namebuf) - 1 && author + len < boemail;
-		     len++)
-			namebuf[len] = author[len];
-		while (0 < len && isspace(namebuf[len-1]))
-			len--;
-		namebuf[len] = '\0';
-	}
-	else
-		len = strlen(namebuf);
+	if (log->email)
+		strbuf_addf(&namemailbuf, " <%.*s>", (int)maillen, mailbuf);
 
-	if (log->email) {
-		size_t room = sizeof(namebuf) - len - 1;
-		int maillen = strlen(emailbuf);
-		snprintf(namebuf + len, room, " <%.*s>", maillen, emailbuf);
-	}
-
-	item = string_list_insert(&log->list, namebuf);
+	item = string_list_insert(&log->list, namemailbuf.buf);
 	if (item->util == NULL)
 		item->util = xcalloc(1, sizeof(struct string_list));
 
diff --git a/commit.h b/commit.h
index 0f469e507d..c16c8a7534 100644
--- a/commit.h
+++ b/commit.h
@@ -89,6 +89,7 @@ struct pretty_print_context {
 	char *notes_message;
 	struct reflog_walk_info *reflog_info;
 	const char *output_encoding;
+	struct string_list *mailmap;
 	int color;
 };
 
diff --git a/log-tree.c b/log-tree.c
index f8487f8a8a..5dc45c4812 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -681,6 +681,7 @@ void show_log(struct rev_info *opt)
 	ctx.preserve_subject = opt->preserve_subject;
 	ctx.reflog_info = opt->reflog_info;
 	ctx.fmt = opt->commit_format;
+	ctx.mailmap = opt->mailmap;
 	ctx.color = opt->diffopt.use_color;
 	pretty_print_commit(&ctx, commit, &msgbuf);
 
diff --git a/mailmap.c b/mailmap.c
index b16542febe..2a7b36628c 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -235,6 +235,7 @@ int read_mailmap(struct string_list *map, char **repo_abbrev)
 	int err = 0;
 
 	map->strdup_strings = 1;
+	map->cmp = strcasecmp;
 
 	if (!git_mailmap_blob && is_bare_repository())
 		git_mailmap_blob = "HEAD:.mailmap";
@@ -253,60 +254,95 @@ void clear_mailmap(struct string_list *map)
 	debug_mm("mailmap: cleared\n");
 }
 
-int map_user(struct string_list *map,
-	     char *email, int maxlen_email, char *name, int maxlen_name)
+/*
+ * Look for an entry in map that match string[0:len]; string[len]
+ * does not have to be NUL (but it could be).
+ */
+static struct string_list_item *lookup_prefix(struct string_list *map,
+					      const char *string, size_t len)
+{
+	int i = string_list_find_insert_index(map, string, 1);
+	if (i < 0) {
+		/* exact match */
+		i = -1 - i;
+		if (!string[len])
+			return &map->items[i];
+		/*
+		 * that map entry matches exactly to the string, including
+		 * the cruft at the end beyond "len".  That is not a match
+		 * with string[0:len] that we are looking for.
+		 */
+	} else if (!string[len]) {
+		/*
+		 * asked with the whole string, and got nothing.  No
+		 * matching entry can exist in the map.
+		 */
+		return NULL;
+	}
+
+	/*
+	 * i is at the exact match to an overlong key, or location the
+	 * overlong key would be inserted, which must come after the
+	 * real location of the key if one exists.
+	 */
+	while (0 <= --i && i < map->nr) {
+		int cmp = strncasecmp(map->items[i].string, string, len);
+		if (cmp < 0)
+			/*
+			 * "i" points at a key definitely below the prefix;
+			 * the map does not have string[0:len] in it.
+			 */
+			break;
+		else if (!cmp && !map->items[i].string[len])
+			/* found it */
+			return &map->items[i];
+		/*
+		 * otherwise, the string at "i" may be string[0:len]
+		 * followed by a string that sorts later than string[len:];
+		 * keep trying.
+		 */
+	}
+	return NULL;
+}
+
+int map_user(struct string_list *map,
+			 const char **email, size_t *emaillen,
+			 const char **name, size_t *namelen)
 {
-	char *end_of_email;
 	struct string_list_item *item;
 	struct mailmap_entry *me;
-	char buf[1024], *mailbuf;
-	int i;
 
-	/* figure out space requirement for email */
-	end_of_email = strchr(email, '>');
-	if (!end_of_email) {
-		/* email passed in might not be wrapped in <>, but end with a \0 */
-		end_of_email = memchr(email, '\0', maxlen_email);
-		if (!end_of_email)
-			return 0;
-	}
-	if (end_of_email - email + 1 < sizeof(buf))
-		mailbuf = buf;
-	else
-		mailbuf = xmalloc(end_of_email - email + 1);
+	debug_mm("map_user: map '%.*s' <%.*s>\n",
+		 *name, *namelen, *emaillen, *email);
 
-	/* downcase the email address */
-	for (i = 0; i < end_of_email - email; i++)
-		mailbuf[i] = tolower(email[i]);
-	mailbuf[i] = 0;
-
-	debug_mm("map_user: map '%s' <%s>\n", name, mailbuf);
-	item = string_list_lookup(map, mailbuf);
+	item = lookup_prefix(map, *email, *emaillen);
 	if (item != NULL) {
 		me = (struct mailmap_entry *)item->util;
 		if (me->namemap.nr) {
 			/* The item has multiple items, so we'll look up on name too */
 			/* If the name is not found, we choose the simple entry      */
-			struct string_list_item *subitem = string_list_lookup(&me->namemap, name);
+			struct string_list_item *subitem;
+			subitem = lookup_prefix(&me->namemap, *name, *namelen);
 			if (subitem)
 				item = subitem;
 		}
 	}
-	if (mailbuf != buf)
-		free(mailbuf);
 	if (item != NULL) {
 		struct mailmap_info *mi = (struct mailmap_info *)item->util;
-		if (mi->name == NULL && (mi->email == NULL || maxlen_email == 0)) {
+		if (mi->name == NULL && mi->email == NULL) {
 			debug_mm("map_user:  -- (no simple mapping)\n");
 			return 0;
 		}
-		if (maxlen_email && mi->email)
-			strlcpy(email, mi->email, maxlen_email);
-		else
-			*end_of_email = '\0';
-		if (maxlen_name && mi->name)
-			strlcpy(name, mi->name, maxlen_name);
-		debug_mm("map_user:  to '%s' <%s>\n", name, mi->email ? mi->email : "");
+		if (mi->email) {
+				*email = mi->email;
+				*emaillen = strlen(*email);
+		}
+		if (mi->name) {
+				*name = mi->name;
+				*namelen = strlen(*name);
+		}
+		debug_mm("map_user:  to '%.*s' <.*%s>\n", *namelen, *name,
+				 *emaillen, *email);
 		return 1;
 	}
 	debug_mm("map_user:  --\n");
diff --git a/mailmap.h b/mailmap.h
index d5c3664322..ed7c93b05c 100644
--- a/mailmap.h
+++ b/mailmap.h
@@ -4,7 +4,7 @@
 int read_mailmap(struct string_list *map, char **repo_abbrev);
 void clear_mailmap(struct string_list *map);
 
-int map_user(struct string_list *mailmap,
-	     char *email, int maxlen_email, char *name, int maxlen_name);
+int map_user(struct string_list *map,
+			 const char **email, size_t *emaillen, const char **name, size_t *namelen);
 
 #endif
diff --git a/pretty.c b/pretty.c
index 01795de687..07fc062865 100644
--- a/pretty.c
+++ b/pretty.c
@@ -387,56 +387,79 @@ void pp_user_info(const struct pretty_print_context *pp,
 		  const char *what, struct strbuf *sb,
 		  const char *line, const char *encoding)
 {
+	struct strbuf name;
+	struct strbuf mail;
+	struct ident_split ident;
+	int linelen;
+	char *line_end, *date;
+	const char *mailbuf, *namebuf;
+	size_t namelen, maillen;
 	int max_length = 78; /* per rfc2822 */
-	char *date;
-	int namelen;
 	unsigned long time;
 	int tz;
 
 	if (pp->fmt == CMIT_FMT_ONELINE)
 		return;
-	date = strchr(line, '>');
-	if (!date)
+
+	line_end = strchr(line, '\n');
+	if (!line_end) {
+		line_end = strchr(line, '\0');
+		if (!line_end)
+			return;
+	}
+
+	linelen = ++line_end - line;
+	if (split_ident_line(&ident, line, linelen))
 		return;
-	namelen = ++date - line;
-	time = strtoul(date, &date, 10);
+
+
+	mailbuf = ident.mail_begin;
+	maillen = ident.mail_end - ident.mail_begin;
+	namebuf = ident.name_begin;
+	namelen = ident.name_end - ident.name_begin;
+
+	if (pp->mailmap)
+		map_user(pp->mailmap, &mailbuf, &maillen, &namebuf, &namelen);
+
+	strbuf_init(&mail, 0);
+	strbuf_init(&name, 0);
+
+	strbuf_add(&mail, mailbuf, maillen);
+	strbuf_add(&name, namebuf, namelen);
+
+	namelen = name.len + mail.len + 3; /* ' ' + '<' + '>' */
+	time = strtoul(ident.date_begin, &date, 10);
 	tz = strtol(date, NULL, 10);
 
 	if (pp->fmt == CMIT_FMT_EMAIL) {
-		char *name_tail = strchr(line, '<');
-		int display_name_length;
-		if (!name_tail)
-			return;
-		while (line < name_tail && isspace(name_tail[-1]))
-			name_tail--;
-		display_name_length = name_tail - line;
 		strbuf_addstr(sb, "From: ");
-		if (needs_rfc2047_encoding(line, display_name_length, RFC2047_ADDRESS)) {
-			add_rfc2047(sb, line, display_name_length,
-						encoding, RFC2047_ADDRESS);
+		if (needs_rfc2047_encoding(name.buf, name.len, RFC2047_ADDRESS)) {
+			add_rfc2047(sb, name.buf, name.len,
+				    encoding, RFC2047_ADDRESS);
 			max_length = 76; /* per rfc2047 */
-		} else if (needs_rfc822_quoting(line, display_name_length)) {
+		} else if (needs_rfc822_quoting(name.buf, name.len)) {
 			struct strbuf quoted = STRBUF_INIT;
-			add_rfc822_quoted(&quoted, line, display_name_length);
+			add_rfc822_quoted(&quoted, name.buf, name.len);
 			strbuf_add_wrapped_bytes(sb, quoted.buf, quoted.len,
 							-6, 1, max_length);
 			strbuf_release(&quoted);
 		} else {
-			strbuf_add_wrapped_bytes(sb, line, display_name_length,
-							-6, 1, max_length);
+			strbuf_add_wrapped_bytes(sb, name.buf, name.len,
+						 -6, 1, max_length);
 		}
-		if (namelen - display_name_length + last_line_length(sb) > max_length) {
+		if (namelen - name.len + last_line_length(sb) > max_length)
 			strbuf_addch(sb, '\n');
-			if (!isspace(name_tail[0]))
-				strbuf_addch(sb, ' ');
-		}
-		strbuf_add(sb, name_tail, namelen - display_name_length);
-		strbuf_addch(sb, '\n');
+
+		strbuf_addf(sb, " <%s>\n", mail.buf);
 	} else {
-		strbuf_addf(sb, "%s: %.*s%.*s\n", what,
+		strbuf_addf(sb, "%s: %.*s%s <%s>\n", what,
 			      (pp->fmt == CMIT_FMT_FULLER) ? 4 : 0,
-			      "    ", namelen, line);
+			      "    ", name.buf, mail.buf);
 	}
+
+	strbuf_release(&mail);
+	strbuf_release(&name);
+
 	switch (pp->fmt) {
 	case CMIT_FMT_MEDIUM:
 		strbuf_addf(sb, "Date:   %s\n", show_date(time, tz, pp->date_mode));
@@ -586,7 +609,8 @@ char *logmsg_reencode(const struct commit *commit,
 	return out;
 }
 
-static int mailmap_name(char *email, int email_len, char *name, int name_len)
+static int mailmap_name(const char **email, size_t *email_len,
+			const char **name, size_t *name_len)
 {
 	static struct string_list *mail_map;
 	if (!mail_map) {
@@ -603,36 +627,26 @@ static size_t format_person_part(struct strbuf *sb, char part,
 	const int placeholder_len = 2;
 	int tz;
 	unsigned long date = 0;
-	char person_name[1024];
-	char person_mail[1024];
 	struct ident_split s;
-	const char *name_start, *name_end, *mail_start, *mail_end;
+	const char *name, *mail;
+	size_t maillen, namelen;
 
 	if (split_ident_line(&s, msg, len) < 0)
 		goto skip;
 
-	name_start = s.name_begin;
-	name_end = s.name_end;
-	mail_start = s.mail_begin;
-	mail_end = s.mail_end;
+	name = s.name_begin;
+	namelen = s.name_end - s.name_begin;
+	mail = s.mail_begin;
+	maillen = s.mail_end - s.mail_begin;
 
-	if (part == 'N' || part == 'E') { /* mailmap lookup */
-		snprintf(person_name, sizeof(person_name), "%.*s",
-			 (int)(name_end - name_start), name_start);
-		snprintf(person_mail, sizeof(person_mail), "%.*s",
-			 (int)(mail_end - mail_start), mail_start);
-		mailmap_name(person_mail, sizeof(person_mail), person_name, sizeof(person_name));
-		name_start = person_name;
-		name_end = name_start + strlen(person_name);
-		mail_start = person_mail;
-		mail_end = mail_start +  strlen(person_mail);
-	}
+	if (part == 'N' || part == 'E') /* mailmap lookup */
+		mailmap_name(&mail, &maillen, &name, &namelen);
 	if (part == 'n' || part == 'N') {	/* name */
-		strbuf_add(sb, name_start, name_end-name_start);
+		strbuf_add(sb, name, namelen);
 		return placeholder_len;
 	}
 	if (part == 'e' || part == 'E') {	/* email */
-		strbuf_add(sb, mail_start, mail_end-mail_start);
+		strbuf_add(sb, mail, maillen);
 		return placeholder_len;
 	}
 
diff --git a/revision.c b/revision.c
index 95d21e6472..d7562ee500 100644
--- a/revision.c
+++ b/revision.c
@@ -13,6 +13,7 @@
 #include "decorate.h"
 #include "log-tree.h"
 #include "string-list.h"
+#include "mailmap.h"
 
 volatile show_early_output_fn_t show_early_output;
 
@@ -2219,6 +2220,51 @@ static int rewrite_parents(struct rev_info *revs, struct commit *commit)
 	return 0;
 }
 
+static int commit_rewrite_person(struct strbuf *buf, const char *what, struct string_list *mailmap)
+{
+	char *person, *endp;
+	size_t len, namelen, maillen;
+	const char *name;
+	const char *mail;
+	struct ident_split ident;
+
+	person = strstr(buf->buf, what);
+	if (!person)
+		return 0;
+
+	person += strlen(what);
+	endp = strchr(person, '\n');
+	if (!endp)
+		return 0;
+
+	len = endp - person;
+
+	if (split_ident_line(&ident, person, len))
+		return 0;
+
+	mail = ident.mail_begin;
+	maillen = ident.mail_end - ident.mail_begin;
+	name = ident.name_begin;
+	namelen = ident.name_end - ident.name_begin;
+
+	if (map_user(mailmap, &mail, &maillen, &name, &namelen)) {
+		struct strbuf namemail = STRBUF_INIT;
+
+		strbuf_addf(&namemail, "%.*s <%.*s>",
+			    (int)namelen, name, (int)maillen, mail);
+
+		strbuf_splice(buf, ident.name_begin - buf->buf,
+			      ident.mail_end - ident.name_begin + 1,
+			      namemail.buf, namemail.len);
+
+		strbuf_release(&namemail);
+
+		return 1;
+	}
+
+	return 0;
+}
+
 static int commit_match(struct commit *commit, struct rev_info *opt)
 {
 	int retval;
@@ -2237,6 +2283,14 @@ static int commit_match(struct commit *commit, struct rev_info *opt)
 	if (buf.len)
 		strbuf_addstr(&buf, commit->buffer);
 
+	if (opt->grep_filter.header_list && opt->mailmap) {
+		if (!buf.len)
+			strbuf_addstr(&buf, commit->buffer);
+
+		commit_rewrite_person(&buf, "\nauthor ", opt->mailmap);
+		commit_rewrite_person(&buf, "\ncommitter ", opt->mailmap);
+	}
+
 	/* Append "fake" message parts as needed */
 	if (opt->show_notes) {
 		if (!buf.len)
diff --git a/revision.h b/revision.h
index a395c3639a..5da09ee3ef 100644
--- a/revision.h
+++ b/revision.h
@@ -144,6 +144,7 @@ struct rev_info {
 	const char	*subject_prefix;
 	int		no_inline;
 	int		show_log_size;
+	struct string_list *mailmap;
 
 	/* Filter by commit log message */
 	struct grep_opt	grep_filter;
diff --git a/string-list.c b/string-list.c
index 480173fe6d..aabb25ef4c 100644
--- a/string-list.c
+++ b/string-list.c
@@ -7,10 +7,11 @@ static int get_entry_index(const struct string_list *list, const char *string,
 		int *exact_match)
 {
 	int left = -1, right = list->nr;
+	compare_strings_fn cmp = list->cmp ? list->cmp : strcmp;
 
 	while (left + 1 < right) {
 		int middle = (left + right) / 2;
-		int compare = strcmp(string, list->items[middle].string);
+		int compare = cmp(string, list->items[middle].string);
 		if (compare < 0)
 			right = middle;
 		else if (compare > 0)
@@ -96,8 +97,9 @@ void string_list_remove_duplicates(struct string_list *list, int free_util)
 {
 	if (list->nr > 1) {
 		int src, dst;
+		compare_strings_fn cmp = list->cmp ? list->cmp : strcmp;
 		for (src = dst = 1; src < list->nr; src++) {
-			if (!strcmp(list->items[dst - 1].string, list->items[src].string)) {
+			if (!cmp(list->items[dst - 1].string, list->items[src].string)) {
 				if (list->strdup_strings)
 					free(list->items[src].string);
 				if (free_util)
@@ -210,15 +212,20 @@ struct string_list_item *string_list_append(struct string_list *list,
 			list->strdup_strings ? xstrdup(string) : (char *)string);
 }
 
+/* Yuck */
+static compare_strings_fn compare_for_qsort;
+
+/* Only call this from inside sort_string_list! */
 static int cmp_items(const void *a, const void *b)
 {
 	const struct string_list_item *one = a;
 	const struct string_list_item *two = b;
-	return strcmp(one->string, two->string);
+	return compare_for_qsort(one->string, two->string);
 }
 
 void sort_string_list(struct string_list *list)
 {
+	compare_for_qsort = list->cmp ? list->cmp : strcmp;
 	qsort(list->items, list->nr, sizeof(*list->items), cmp_items);
 }
 
@@ -226,8 +233,10 @@ struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
 						     const char *string)
 {
 	int i;
+	compare_strings_fn cmp = list->cmp ? list->cmp : strcmp;
+
 	for (i = 0; i < list->nr; i++)
-		if (!strcmp(string, list->items[i].string))
+		if (!cmp(string, list->items[i].string))
 			return list->items + i;
 	return NULL;
 }
diff --git a/string-list.h b/string-list.h
index db1284861a..de6769c92d 100644
--- a/string-list.h
+++ b/string-list.h
@@ -5,10 +5,14 @@ struct string_list_item {
 	char *string;
 	void *util;
 };
+
+typedef int (*compare_strings_fn)(const char *, const char *);
+
 struct string_list {
 	struct string_list_item *items;
 	unsigned int nr, alloc;
 	unsigned int strdup_strings:1;
+	compare_strings_fn cmp; /* NULL uses strcmp() */
 };
 
 #define STRING_LIST_INIT_NODUP { NULL, 0, 0, 0 }
diff --git a/t/t4203-mailmap.sh b/t/t4203-mailmap.sh
index aae30d97b1..842b7549ec 100755
--- a/t/t4203-mailmap.sh
+++ b/t/t4203-mailmap.sh
@@ -337,6 +337,62 @@ test_expect_success 'Log output (complex mapping)' '
 	test_cmp expect actual
 '
 
+cat >expect <<\EOF
+Author: CTO <cto@company.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Other Author <other@author.xx>
+Author: Other Author <other@author.xx>
+Author: Some Dude <some@dude.xx>
+Author: A U Thor <author@example.com>
+EOF
+
+test_expect_success 'Log output with --use-mailmap' '
+	git log --use-mailmap | grep Author >actual &&
+	test_cmp expect actual
+'
+
+cat >expect <<\EOF
+Author: CTO <cto@company.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Other Author <other@author.xx>
+Author: Other Author <other@author.xx>
+Author: Some Dude <some@dude.xx>
+Author: A U Thor <author@example.com>
+EOF
+
+test_expect_success 'Log output with log.mailmap' '
+	git -c log.mailmap=True log | grep Author >actual &&
+	test_cmp expect actual
+'
+
+cat >expect <<\EOF
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+EOF
+
+test_expect_success 'Grep author with --use-mailmap' '
+	git log --use-mailmap --author Santa | grep Author >actual &&
+	test_cmp expect actual
+'
+cat >expect <<\EOF
+Author: Santa Claus <santa.claus@northpole.xx>
+Author: Santa Claus <santa.claus@northpole.xx>
+EOF
+
+test_expect_success 'Grep author with log.mailmap' '
+	git -c log.mailmap=True log --author Santa | grep Author >actual &&
+	test_cmp expect actual
+'
+
+>expect
+
+test_expect_success 'Only grep replaced author with --use-mailmap' '
+	git log --use-mailmap --author "<cto@coompany.xx>" >actual &&
+	test_cmp expect actual
+'
+
 # git blame
 cat >expect <<\EOF
 ^OBJI (A U Thor     DATE 1) one