diff --git a/.gitignore b/.gitignore
index e875c590545..cc064a4817a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,6 +14,7 @@
 /bin-wrappers/
 /git
 /git-add
+/git-ahead-behind
 /git-am
 /git-annotate
 /git-apply
diff --git a/Documentation/git-ahead-behind.txt b/Documentation/git-ahead-behind.txt
new file mode 100644
index 00000000000..0e2f989a1a0
--- /dev/null
+++ b/Documentation/git-ahead-behind.txt
@@ -0,0 +1,62 @@
+git-ahead-behind(1)
+===================
+
+NAME
+----
+git-ahead-behind - Count the commits on each side of a revision range
+
+SYNOPSIS
+--------
+[verse]
+'git ahead-behind' --base=<ref> [ --stdin | <revs> ]
+
+DESCRIPTION
+-----------
+
+Given a list of commit ranges, report the number of commits reachable from
+each of the sides of the range, but not the other. Consider a commit range
+specified as `<base>...<tip>`, allowing for the following definitions:
+
+* The `<tip>` is *ahead* of `<base>` by the number of commits reachable
+  from `<tip>` but not reachable from `<base>`. This is the same as the
+  number of the commits in the range `<base>..<tip>`.
+
+* The `<tip>` is *behind* `<base>` by the number of commits reachable from
+  `<base>` but not reachble from `<tip>`. This is the same as the number
+  of commits in the range `<tip>..<base>`.
+
+The sum of the ahead and behind counts equals the number of commits in the
+symmetric difference, the range `<base>...<tip>`.
+
+Multiple revisions may be specified, and they are all compared against a
+common base revision, as specified by the `--base` option. The values are
+reported to stdout one line at a time as follows:
+
+---
+  <rev> <ahead> <behind>
+---
+
+There will be exactly one line per input revision, but the lines may be
+in an arbitrary order.
+
+
+OPTIONS
+-------
+--base=<ref>::
+	Specify that `<ref>` should be used as a common base for all
+	provided revisions that are not specified in the form of a range.
+
+--stdin::
+	Read revision tips and ranges from stdin instead of from the
+	command-line.
+
+
+SEE ALSO
+--------
+linkgit:git-branch[1]
+linkgit:git-rev-list[1]
+linkgit:git-tag[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite
diff --git a/Makefile b/Makefile
index 50ee51fde32..691f84e8d4e 100644
--- a/Makefile
+++ b/Makefile
@@ -1199,6 +1199,7 @@ LIB_OBJS += xdiff-interface.o
 LIB_OBJS += zlib.o
 
 BUILTIN_OBJS += builtin/add.o
+BUILTIN_OBJS += builtin/ahead-behind.o
 BUILTIN_OBJS += builtin/am.o
 BUILTIN_OBJS += builtin/annotate.o
 BUILTIN_OBJS += builtin/apply.o
diff --git a/builtin.h b/builtin.h
index 46cc7897898..1ae168fa3e3 100644
--- a/builtin.h
+++ b/builtin.h
@@ -108,6 +108,7 @@ void setup_auto_pager(const char *cmd, int def);
 int is_builtin(const char *s);
 
 int cmd_add(int argc, const char **argv, const char *prefix);
+int cmd_ahead_behind(int argc, const char **argv, const char *prefix);
 int cmd_am(int argc, const char **argv, const char *prefix);
 int cmd_annotate(int argc, const char **argv, const char *prefix);
 int cmd_apply(int argc, const char **argv, const char *prefix);
diff --git a/builtin/ahead-behind.c b/builtin/ahead-behind.c
new file mode 100644
index 00000000000..a56cc565def
--- /dev/null
+++ b/builtin/ahead-behind.c
@@ -0,0 +1,30 @@
+#include "builtin.h"
+#include "parse-options.h"
+#include "config.h"
+
+static const char * const ahead_behind_usage[] = {
+	N_("git ahead-behind --base=<ref> [ --stdin | <revs> ]"),
+	NULL
+};
+
+int cmd_ahead_behind(int argc, const char **argv, const char *prefix)
+{
+	const char *base_ref = NULL;
+	int from_stdin = 0;
+
+	struct option ahead_behind_opts[] = {
+		OPT_STRING('b', "base", &base_ref, N_("base"), N_("base reference to process")),
+		OPT_BOOL(0 , "stdin", &from_stdin, N_("read rev names from stdin")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, NULL, ahead_behind_opts,
+			     ahead_behind_usage, PARSE_OPT_KEEP_UNKNOWN_OPT);
+
+	if (!base_ref)
+		usage_with_options(ahead_behind_usage, ahead_behind_opts);
+
+	git_config(git_default_config, NULL);
+
+	return 0;
+}
diff --git a/git.c b/git.c
index 6171fd6769d..64e3d493561 100644
--- a/git.c
+++ b/git.c
@@ -467,6 +467,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 
 static struct cmd_struct commands[] = {
 	{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
+	{ "ahead-behind", cmd_ahead_behind, RUN_SETUP },
 	{ "am", cmd_am, RUN_SETUP | NEED_WORK_TREE },
 	{ "annotate", cmd_annotate, RUN_SETUP },
 	{ "apply", cmd_apply, RUN_SETUP_GENTLY },
diff --git a/t/t4218-ahead-behind.sh b/t/t4218-ahead-behind.sh
new file mode 100755
index 00000000000..bc08f1207a0
--- /dev/null
+++ b/t/t4218-ahead-behind.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+test_description='git ahead-behind command-line options'
+
+. ./test-lib.sh
+
+test_expect_success 'git ahead-behind -h' '
+	test_must_fail git ahead-behind -h >out &&
+	grep "usage:" out
+'
+
+test_expect_success 'git ahead-behind without --base' '
+	test_must_fail git ahead-behind HEAD 2>err &&
+	grep "usage:" err
+'
+
+test_done
