diff --git a/Documentation/config.txt b/Documentation/config.txt
index abeb82b2c6..e55dae1806 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -84,6 +84,17 @@ customary UNIX fashion.
 
 Some variables may require a special value format.
 
+Includes
+~~~~~~~~
+
+You can include one config file from another by setting the special
+`include.path` variable to the name of the file to be included. The
+included file is expanded immediately, as if its contents had been
+found at the location of the include directive. If the value of the
+`include.path` variable is a relative path, the path is considered to be
+relative to the configuration file in which the include directive was
+found. See below for examples.
+
 Example
 ~~~~~~~
 
@@ -106,6 +117,10 @@ Example
 		gitProxy="ssh" for "kernel.org"
 		gitProxy=default-proxy ; for the rest
 
+	[include]
+		path = /path/to/foo.inc ; include by absolute path
+		path = foo ; expand "foo" relative to the current file
+
 Variables
 ~~~~~~~~~
 
diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index e7ecf5d803..aa8303b1ad 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -178,6 +178,11 @@ See also <<FILES>>.
 	Opens an editor to modify the specified config file; either
 	'--system', '--global', or repository (default).
 
+--includes::
+--no-includes::
+	Respect `include.*` directives in config files when looking up
+	values. Defaults to on.
+
 [[FILES]]
 FILES
 -----
diff --git a/Documentation/technical/api-config.txt b/Documentation/technical/api-config.txt
index f428c5c486..c60b6b3c93 100644
--- a/Documentation/technical/api-config.txt
+++ b/Documentation/technical/api-config.txt
@@ -95,6 +95,28 @@ string is given, prints an error message and returns -1.
 Similar to `git_config_string`, but expands `~` or `~user` into the
 user's home directory when found at the beginning of the path.
 
+Include Directives
+------------------
+
+By default, the config parser does not respect include directives.
+However, a caller can use the special `git_config_include` wrapper
+callback to support them. To do so, you simply wrap your "real" callback
+function and data pointer in a `struct config_include_data`, and pass
+the wrapper to the regular config-reading functions. For example:
+
+-------------------------------------------
+int read_file_with_include(const char *file, config_fn_t fn, void *data)
+{
+	struct config_include_data inc = CONFIG_INCLUDE_INIT;
+	inc.fn = fn;
+	inc.data = data;
+	return git_config_from_file(git_config_include, file, &inc);
+}
+-------------------------------------------
+
+`git_config` respects includes automatically. The lower-level
+`git_config_from_file` does not.
+
 Writing Config Files
 --------------------
 
diff --git a/builtin/config.c b/builtin/config.c
index d35c06ae51..09bf778168 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -25,6 +25,7 @@ static const char *given_config_file;
 static int actions, types;
 static const char *get_color_slot, *get_colorbool_slot;
 static int end_null;
+static int respect_includes = -1;
 
 #define ACTION_GET (1<<0)
 #define ACTION_GET_ALL (1<<1)
@@ -74,6 +75,7 @@ static struct option builtin_config_options[] = {
 	OPT_BIT(0, "path", &types, "value is a path (file or directory name)", TYPE_PATH),
 	OPT_GROUP("Other"),
 	OPT_BOOLEAN('z', "null", &end_null, "terminate values with NUL byte"),
+	OPT_BOOL(0, "includes", &respect_includes, "respect include directives on lookup"),
 	OPT_END(),
 };
 
@@ -161,6 +163,9 @@ static int get_value(const char *key_, const char *regex_)
 	int ret = -1;
 	char *global = NULL, *repo_config = NULL;
 	const char *system_wide = NULL, *local;
+	struct config_include_data inc = CONFIG_INCLUDE_INIT;
+	config_fn_t fn;
+	void *data;
 
 	local = config_exclusive_filename;
 	if (!local) {
@@ -213,19 +218,28 @@ static int get_value(const char *key_, const char *regex_)
 		}
 	}
 
+	fn = show_config;
+	data = NULL;
+	if (respect_includes) {
+		inc.fn = fn;
+		inc.data = data;
+		fn = git_config_include;
+		data = &inc;
+	}
+
 	if (do_all && system_wide)
-		git_config_from_file(show_config, system_wide, NULL);
+		git_config_from_file(fn, system_wide, data);
 	if (do_all && global)
-		git_config_from_file(show_config, global, NULL);
+		git_config_from_file(fn, global, data);
 	if (do_all)
-		git_config_from_file(show_config, local, NULL);
-	git_config_from_parameters(show_config, NULL);
+		git_config_from_file(fn, local, data);
+	git_config_from_parameters(fn, data);
 	if (!do_all && !seen)
-		git_config_from_file(show_config, local, NULL);
+		git_config_from_file(fn, local, data);
 	if (!do_all && !seen && global)
-		git_config_from_file(show_config, global, NULL);
+		git_config_from_file(fn, global, data);
 	if (!do_all && !seen && system_wide)
-		git_config_from_file(show_config, system_wide, NULL);
+		git_config_from_file(fn, system_wide, data);
 
 	free(key);
 	if (regexp) {
@@ -384,6 +398,9 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 			config_exclusive_filename = given_config_file;
 	}
 
+	if (respect_includes == -1)
+		respect_includes = !config_exclusive_filename;
+
 	if (end_null) {
 		term = '\0';
 		delim = '\n';
diff --git a/cache.h b/cache.h
index 10afd71d43..65c1513a40 100644
--- a/cache.h
+++ b/cache.h
@@ -1138,6 +1138,14 @@ extern const char *get_commit_output_encoding(void);
 
 extern int git_config_parse_parameter(const char *, config_fn_t fn, void *data);
 
+struct config_include_data {
+	int depth;
+	config_fn_t fn;
+	void *data;
+};
+#define CONFIG_INCLUDE_INIT { 0 }
+extern int git_config_include(const char *name, const char *value, void *data);
+
 extern const char *config_exclusive_filename;
 
 #define MAX_GITNAME (1000)
diff --git a/config.c b/config.c
index 40f9c6d103..e3fcf7553c 100644
--- a/config.c
+++ b/config.c
@@ -28,6 +28,69 @@ static int zlib_compression_seen;
 
 const char *config_exclusive_filename = NULL;
 
+#define MAX_INCLUDE_DEPTH 10
+static const char include_depth_advice[] =
+"exceeded maximum include depth (%d) while including\n"
+"	%s\n"
+"from\n"
+"	%s\n"
+"Do you have circular includes?";
+static int handle_path_include(const char *path, struct config_include_data *inc)
+{
+	int ret = 0;
+	struct strbuf buf = STRBUF_INIT;
+
+	/*
+	 * Use an absolute path as-is, but interpret relative paths
+	 * based on the including config file.
+	 */
+	if (!is_absolute_path(path)) {
+		char *slash;
+
+		if (!cf || !cf->name)
+			return error("relative config includes must come from files");
+
+		slash = find_last_dir_sep(cf->name);
+		if (slash)
+			strbuf_add(&buf, cf->name, slash - cf->name + 1);
+		strbuf_addstr(&buf, path);
+		path = buf.buf;
+	}
+
+	if (!access(path, R_OK)) {
+		if (++inc->depth > MAX_INCLUDE_DEPTH)
+			die(include_depth_advice, MAX_INCLUDE_DEPTH, path,
+			    cf && cf->name ? cf->name : "the command line");
+		ret = git_config_from_file(git_config_include, path, inc);
+		inc->depth--;
+	}
+	strbuf_release(&buf);
+	return ret;
+}
+
+int git_config_include(const char *var, const char *value, void *data)
+{
+	struct config_include_data *inc = data;
+	const char *type;
+	int ret;
+
+	/*
+	 * Pass along all values, including "include" directives; this makes it
+	 * possible to query information on the includes themselves.
+	 */
+	ret = inc->fn(var, value, inc->data);
+	if (ret < 0)
+		return ret;
+
+	type = skip_prefix(var, "include.");
+	if (!type)
+		return ret;
+
+	if (!strcmp(type, "path"))
+		ret = handle_path_include(value, inc);
+	return ret;
+}
+
 static void lowercase(char *p)
 {
 	for (; *p; p++)
@@ -921,9 +984,13 @@ int git_config(config_fn_t fn, void *data)
 {
 	char *repo_config = NULL;
 	int ret;
+	struct config_include_data inc = CONFIG_INCLUDE_INIT;
+
+	inc.fn = fn;
+	inc.data = data;
 
 	repo_config = git_pathdup("config");
-	ret = git_config_early(fn, data, repo_config);
+	ret = git_config_early(git_config_include, &inc, repo_config);
 	if (repo_config)
 		free(repo_config);
 	return ret;
diff --git a/t/t1305-config-include.sh b/t/t1305-config-include.sh
new file mode 100755
index 0000000000..0a27ec48d0
--- /dev/null
+++ b/t/t1305-config-include.sh
@@ -0,0 +1,126 @@
+#!/bin/sh
+
+test_description='test config file include directives'
+. ./test-lib.sh
+
+test_expect_success 'include file by absolute path' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = \"$PWD/one\"" >.gitconfig &&
+	echo 1 >expect &&
+	git config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'include file by relative path' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	echo 1 >expect &&
+	git config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'chained relative paths' '
+	mkdir subdir &&
+	echo "[test]three = 3" >subdir/three &&
+	echo "[include]path = three" >subdir/two &&
+	echo "[include]path = subdir/two" >.gitconfig &&
+	echo 3 >expect &&
+	git config test.three >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'include options can still be examined' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	echo one >expect &&
+	git config include.path >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'listing includes option and expansion' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	cat >expect <<-\EOF &&
+	include.path=one
+	test.one=1
+	EOF
+	git config --list >actual.full &&
+	grep -v ^core actual.full >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'single file lookup does not expand includes by default' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	test_must_fail git config -f .gitconfig test.one &&
+	test_must_fail git config --global test.one &&
+	echo 1 >expect &&
+	git config --includes -f .gitconfig test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'writing config file does not expand includes' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	git config test.two 2 &&
+	echo 2 >expect &&
+	git config --no-includes test.two >actual &&
+	test_cmp expect actual &&
+	test_must_fail git config --no-includes test.one
+'
+
+test_expect_success 'config modification does not affect includes' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	git config test.one 2 &&
+	echo 1 >expect &&
+	git config -f one test.one >actual &&
+	test_cmp expect actual &&
+	cat >expect <<-\EOF &&
+	1
+	2
+	EOF
+	git config --get-all test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'missing include files are ignored' '
+	cat >.gitconfig <<-\EOF &&
+	[include]path = foo
+	[test]value = yes
+	EOF
+	echo yes >expect &&
+	git config test.value >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'absolute includes from command line work' '
+	echo "[test]one = 1" >one &&
+	echo 1 >expect &&
+	git -c include.path="$PWD/one" config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'relative includes from command line fail' '
+	echo "[test]one = 1" >one &&
+	test_must_fail git -c include.path=one config test.one
+'
+
+test_expect_success 'include cycles are detected' '
+	cat >.gitconfig <<-\EOF &&
+	[test]value = gitconfig
+	[include]path = cycle
+	EOF
+	cat >cycle <<-\EOF &&
+	[test]value = cycle
+	[include]path = .gitconfig
+	EOF
+	cat >expect <<-\EOF &&
+	gitconfig
+	cycle
+	EOF
+	test_must_fail git config --get-all test.value 2>stderr &&
+	grep "exceeded maximum include depth" stderr
+'
+
+test_done