diff --git a/Documentation/config.txt b/Documentation/config.txt
index 8d85d1a324..c24abf5871 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2,8 +2,9 @@ CONFIGURATION FILE
 ------------------
 
 The Git configuration file contains a number of variables that affect
-the Git commands' behavior. The `.git/config` file in each repository
-is used to store the configuration for that repository, and
+the Git commands' behavior. The files `.git/config` and optionally
+`config.worktree` (see `extensions.worktreeConfig` below) are each
+repository is used to store the configuration for that repository, and
 `$HOME/.gitconfig` is used to store a per-user configuration as
 fallback values for the `.git/config` file. The file `/etc/gitconfig`
 can be used to store a system-wide default configuration.
@@ -371,6 +372,12 @@ advice.*::
 		editor input from the user.
 --
 
+extensions.worktreeConfig::
+	If set, by default "git config" reads from both "config" and
+	"config.worktree" file in that order. In multiple working
+	directory mode, "config" file is shared while
+	"config.worktree" is per-working directory.
+
 core.fileMode::
 	Tells Git if the executable bit of files in the working tree
 	is to be honored.
diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index 8e240435be..4870e00b89 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -45,13 +45,15 @@ unset an existing `--type` specifier with `--no-type`.
 
 When reading, the values are read from the system, global and
 repository local configuration files by default, and options
-`--system`, `--global`, `--local` and `--file <filename>` can be
-used to tell the command to read from only that location (see <<FILES>>).
+`--system`, `--global`, `--local`, `--worktree` and
+`--file <filename>` can be used to tell the command to read from only
+that location (see <<FILES>>).
 
 When writing, the new value is written to the repository local
 configuration file by default, and options `--system`, `--global`,
-`--file <filename>` can be used to tell the command to write to
-that location (you can say `--local` but that is the default).
+`--worktree`, `--file <filename>` can be used to tell the command to
+write to that location (you can say `--local` but that is the
+default).
 
 This command will fail with non-zero status upon error.  Some exit
 codes are:
@@ -131,6 +133,11 @@ from all available files.
 +
 See also <<FILES>>.
 
+--worktree::
+	Similar to `--local` except that `.git/config.worktree` is
+	read from or written to if `extensions.worktreeConfig` is
+	present. If not it's the same as `--local`.
+
 -f config-file::
 --file config-file::
 	Use the given config file instead of the one specified by GIT_CONFIG.
@@ -281,6 +288,10 @@ $XDG_CONFIG_HOME/git/config::
 $GIT_DIR/config::
 	Repository specific configuration file.
 
+$GIT_DIR/config.worktree::
+	This is optional and is only searched when
+	`extensions.worktreeConfig` is present in $GIT_DIR/config.
+
 If no further options are given, all reading options will read all of these
 files that are available. If the global or the system-wide configuration
 file are not available they will be ignored. If the repository configuration
@@ -299,9 +310,10 @@ configuration file. Note that this also affects options like `--replace-all`
 and `--unset`. *'git config' will only ever change one file at a time*.
 
 You can override these rules either by command-line options or by environment
-variables. The `--global` and the `--system` options will limit the file used
-to the global or system-wide file respectively. The `GIT_CONFIG` environment
-variable has a similar effect, but you can specify any filename you want.
+variables. The `--global`, `--system` and `--worktree` options will limit
+the file used to the global, system-wide or per-worktree file respectively.
+The `GIT_CONFIG` environment variable has a similar effect, but you
+can specify any filename you want.
 
 
 ENVIRONMENT
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index e2ee9fc21b..3f9112db56 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -204,6 +204,43 @@ working trees, it can be used to identify worktrees. For example if
 you only have two working trees, at "/abc/def/ghi" and "/abc/def/ggg",
 then "ghi" or "def/ghi" is enough to point to the former working tree.
 
+CONFIGURATION FILE
+------------------
+By default, the repository "config" file is shared across all working
+directories. If the config variables `core.bare` or `core.worktree`
+are already present in the config file, they will be applied to the
+main working directory only.
+
+In order to have configuration specific to working directories, you
+can turn on "worktreeConfig" extension, e.g.:
+
+------------
+$ git config extensions.worktreeConfig true
+------------
+
+In this mode, specific configuration stays in the path pointed by `git
+rev-parse --git-path config.worktree`. You can add or update
+configuration in this file with `git config --worktree`. Git before
+version 2.20.0 will refuse to access repositories with this extension.
+
+Note that in this file, the exception for `core.bare` and
+`core.worktree` is gone. If you have them before, you need to move
+them to the `config.worktree` of the main working directory. You may
+also take this opportunity to move other configuration that you do not
+want to share to all working directories:
+
+ - `core.worktree` and `core.bare` should never be shared
+
+ - `core.sparseCheckout` is recommended per working directory, unless
+   you are sure you always use sparse checkout for all working
+   directories.
+
+When `git config --worktree` is used to set a configuration variable
+in multiple working directory setup, `extensions.worktreeConfig` will
+be automatically set. The two variables `core.worktree` and
+`core.bare` if present will be moved to `config.worktree` of the main
+working tree.
+
 DETAILS
 -------
 Each linked working tree has a private sub-directory in the repository's
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index e85148f05e..36fcca8087 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -143,6 +143,11 @@ config::
 	if $GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/config" will be
 	used instead.
 
+config.worktree::
+	Working directory specific configuration file for the main
+	working directory in multiple working directory setup (see
+	linkgit:git-worktree[1]).
+
 branches::
 	A slightly deprecated way to store shorthands to be used
 	to specify a URL to 'git fetch', 'git pull' and 'git push'.
@@ -275,6 +280,9 @@ worktrees/<id>/locked::
 	or manually by `git worktree prune`. The file may contain a string
 	explaining why the repository is locked.
 
+worktrees/<id>/config.worktree::
+	Working directory specific configuration file.
+
 SEE ALSO
 --------
 linkgit:git-init[1],
diff --git a/builtin/config.c b/builtin/config.c
index 97b58c4aea..337db7b552 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -5,6 +5,7 @@
 #include "parse-options.h"
 #include "urlmatch.h"
 #include "quote.h"
+#include "worktree.h"
 
 static const char *const builtin_config_usage[] = {
 	N_("git config [<options>]"),
@@ -24,6 +25,7 @@ static char key_delim = ' ';
 static char term = '\n';
 
 static int use_global_config, use_system_config, use_local_config;
+static int use_worktree_config;
 static struct git_config_source given_config_source;
 static int actions, type;
 static char *default_value;
@@ -123,6 +125,7 @@ static struct option builtin_config_options[] = {
 	OPT_BOOL(0, "global", &use_global_config, N_("use global config file")),
 	OPT_BOOL(0, "system", &use_system_config, N_("use system config file")),
 	OPT_BOOL(0, "local", &use_local_config, N_("use repository config file")),
+	OPT_BOOL(0, "worktree", &use_worktree_config, N_("use per-worktree config file")),
 	OPT_STRING('f', "file", &given_config_source.file, N_("file"), N_("use given config file")),
 	OPT_STRING(0, "blob", &given_config_source.blob, N_("blob-id"), N_("read config from given blob object")),
 	OPT_GROUP(N_("Action")),
@@ -602,6 +605,7 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 
 	if (use_global_config + use_system_config + use_local_config +
+	    use_worktree_config +
 	    !!given_config_source.file + !!given_config_source.blob > 1) {
 		error(_("only one config file at a time"));
 		usage_builtin_config();
@@ -645,7 +649,17 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		given_config_source.file = git_etc_gitconfig();
 	else if (use_local_config)
 		given_config_source.file = git_pathdup("config");
-	else if (given_config_source.file) {
+	else if (use_worktree_config) {
+		struct worktree **worktrees = get_worktrees(0);
+		if (repository_format_worktree_config)
+			given_config_source.file = git_pathdup("config.worktree");
+		else if (worktrees[0] && worktrees[1]) {
+			migrate_worktree_config(the_repository);
+			given_config_source.file = git_pathdup("config.worktree");
+		} else
+			given_config_source.file = git_pathdup("config");
+		free_worktrees(worktrees);
+	} else if (given_config_source.file) {
 		if (!is_absolute_path(given_config_source.file) && prefix)
 			given_config_source.file =
 				prefix_filename(prefix, given_config_source.file);
diff --git a/cache.h b/cache.h
index d508f3d4f8..9e9b917e99 100644
--- a/cache.h
+++ b/cache.h
@@ -957,11 +957,13 @@ extern int grafts_replace_parents;
 extern int repository_format_precious_objects;
 extern char *repository_format_partial_clone;
 extern const char *core_partial_clone_filter_default;
+extern int repository_format_worktree_config;
 
 struct repository_format {
 	int version;
 	int precious_objects;
 	char *partial_clone; /* value of extensions.partialclone */
+	int worktree_config;
 	int is_bare;
 	int hash_algo;
 	char *work_tree;
diff --git a/config.c b/config.c
index 3461993f0a..24f68a5208 100644
--- a/config.c
+++ b/config.c
@@ -1695,6 +1695,13 @@ static int do_git_config_sequence(const struct config_options *opts,
 	if (repo_config && !access_or_die(repo_config, R_OK, 0))
 		ret += git_config_from_file(fn, repo_config, data);
 
+	if (repository_format_worktree_config) {
+		char *path = git_pathdup("config.worktree");
+		if (!access_or_die(path, R_OK, 0))
+			ret += git_config_from_file(fn, path, data);
+		free(path);
+	}
+
 	current_parsing_scope = CONFIG_SCOPE_CMDLINE;
 	if (git_config_from_parameters(fn, data) < 0)
 		die(_("unable to parse command-line config"));
diff --git a/environment.c b/environment.c
index 3f3c8746c2..268310b3dc 100644
--- a/environment.c
+++ b/environment.c
@@ -33,6 +33,7 @@ int ref_paranoia = -1;
 int repository_format_precious_objects;
 char *repository_format_partial_clone;
 const char *core_partial_clone_filter_default;
+int repository_format_worktree_config;
 const char *git_commit_encoding;
 const char *git_log_output_encoding;
 const char *apply_default_whitespace;
diff --git a/setup.c b/setup.c
index b24c811c1c..6169193946 100644
--- a/setup.c
+++ b/setup.c
@@ -423,7 +423,9 @@ static int check_repo_format(const char *var, const char *value, void *vdata)
 			if (!value)
 				return config_error_nonbool(var);
 			data->partial_clone = xstrdup(value);
-		} else
+		} else if (!strcmp(ext, "worktreeconfig"))
+			data->worktree_config = git_config_bool(var, value);
+		else
 			string_list_append(&data->unknown_extensions, ext);
 	} else if (strcmp(var, "core.bare") == 0) {
 		data->is_bare = git_config_bool(var, value);
@@ -466,6 +468,7 @@ static int check_repository_format_gently(const char *gitdir, struct repository_
 
 	repository_format_precious_objects = candidate->precious_objects;
 	repository_format_partial_clone = candidate->partial_clone;
+	repository_format_worktree_config = candidate->worktree_config;
 	string_list_clear(&candidate->unknown_extensions, 0);
 	if (!has_common) {
 		if (candidate->is_bare != -1) {
diff --git a/t/t2029-worktree-config.sh b/t/t2029-worktree-config.sh
new file mode 100755
index 0000000000..4ebdf13cf9
--- /dev/null
+++ b/t/t2029-worktree-config.sh
@@ -0,0 +1,82 @@
+#!/bin/sh
+
+test_description="config file in multi worktree"
+
+. ./test-lib.sh
+
+cmp_config() {
+	if [ "$1" = "-C" ]; then
+		shift &&
+		GD="-C $1" &&
+		shift
+	else
+		GD=
+	fi &&
+	echo "$1" >expected &&
+	shift &&
+	git $GD config "$@" >actual &&
+	test_cmp expected actual
+}
+
+test_expect_success 'setup' '
+	test_commit start &&
+	git config --worktree per.worktree is-ok &&
+	git worktree add wt1 &&
+	git worktree add wt2 &&
+	git config --worktree per.worktree is-ok &&
+	cmp_config true extensions.worktreeConfig
+'
+
+test_expect_success 'config is shared as before' '
+	git config this.is shared &&
+	cmp_config shared this.is &&
+	cmp_config -C wt1 shared this.is &&
+	cmp_config -C wt2 shared this.is
+'
+
+test_expect_success 'config is shared (set from another worktree)' '
+	git -C wt1 config that.is also-shared &&
+	cmp_config also-shared that.is &&
+	cmp_config -C wt1 also-shared that.is &&
+	cmp_config -C wt2 also-shared that.is
+'
+
+test_expect_success 'config private to main worktree' '
+	git config --worktree this.is for-main &&
+	cmp_config for-main this.is &&
+	cmp_config -C wt1 shared this.is &&
+	cmp_config -C wt2 shared this.is
+'
+
+test_expect_success 'config private to linked worktree' '
+	git -C wt1 config --worktree this.is for-wt1 &&
+	cmp_config for-main this.is &&
+	cmp_config -C wt1 for-wt1 this.is &&
+	cmp_config -C wt2 shared this.is
+'
+
+test_expect_success 'core.bare no longer for main only' '
+	git config core.bare true &&
+	cmp_config true core.bare &&
+	cmp_config -C wt1 true core.bare &&
+	cmp_config -C wt2 true core.bare &&
+	git config --unset core.bare
+'
+
+test_expect_success 'config.worktree no longer read without extension' '
+	git config --unset extensions.worktreeConfig &&
+	cmp_config shared this.is &&
+	cmp_config -C wt1 shared this.is &&
+	cmp_config -C wt2 shared this.is
+'
+
+test_expect_success 'config --worktree migrate core.bare and core.worktree' '
+	git config core.bare true &&
+	git config --worktree foo.bar true &&
+	cmp_config true extensions.worktreeConfig &&
+	cmp_config true foo.bar &&
+	cmp_config true core.bare &&
+	! git -C wt1 config core.bare
+'
+
+test_done
diff --git a/worktree.c b/worktree.c
index b0d0b5426d..a239f99bdc 100644
--- a/worktree.c
+++ b/worktree.c
@@ -5,6 +5,7 @@
 #include "worktree.h"
 #include "dir.h"
 #include "wt-status.h"
+#include "config.h"
 
 void free_worktrees(struct worktree **worktrees)
 {
@@ -508,3 +509,43 @@ int other_head_refs(each_ref_fn fn, void *cb_data)
 	free_worktrees(worktrees);
 	return ret;
 }
+
+void migrate_worktree_config(struct repository *r)
+{
+	struct strbuf worktree_path = STRBUF_INIT;
+	struct strbuf main_path = STRBUF_INIT;
+	struct repository_format format;
+
+	assert(repository_format_worktree_config == 0);
+
+	strbuf_git_common_path(&worktree_path, r, "config.worktree");
+	strbuf_git_path(&main_path, "config");
+
+	read_repository_format(&format, main_path.buf);
+	assert(format.worktree_config == 0);
+
+	if (format.is_bare >= 0) {
+		git_config_set_in_file(worktree_path.buf,
+				       "core.bare", "true");
+		git_config_set_in_file(main_path.buf,
+				       "core.bare", NULL);
+	}
+	if (format.work_tree) {
+		git_config_set_in_file(worktree_path.buf,
+				       "core.worktree",
+				       format.work_tree);
+		git_config_set_in_file(main_path.buf,
+				       "core.worktree", NULL);
+	}
+
+	git_config_set_in_file(main_path.buf,
+			       "extensions.worktreeConfig", "true");
+	if (format.version == 0)
+		git_config_set_in_file(main_path.buf,
+				       "core.repositoryFormatVersion", "1");
+
+	repository_format_worktree_config = 1;
+
+	strbuf_release(&main_path);
+	strbuf_release(&worktree_path);
+}
diff --git a/worktree.h b/worktree.h
index df3fc30f73..b27b407d1b 100644
--- a/worktree.h
+++ b/worktree.h
@@ -108,4 +108,10 @@ extern const char *worktree_git_path(const struct worktree *wt,
 				     const char *fmt, ...)
 	__attribute__((format (printf, 2, 3)));
 
+/*
+ * Called to add extensions.worktreeConfig to $GIT_DIR/config and move
+ * main worktree specific config variables to $GIT_DIR/config.worktree.
+ */
+void migrate_worktree_config(struct repository *r);
+
 #endif
