diff --git a/t/t1305-config-include.sh b/t/t1305-config-include.sh
index 6e51f892f320..8a5ba4b884d3 100755
--- a/t/t1305-config-include.sh
+++ b/t/t1305-config-include.sh
@@ -396,4 +396,70 @@ test_expect_success 'onbranch without repository but explicit nonexistent Git di
 	test_must_fail nongit git --git-dir=nonexistent config get foo.bar
 '
 
+# worktree: conditional include tests
+
+test_expect_success 'conditional include, worktree bare repo' '
+	git init --bare wt-bare &&
+	(
+		cd wt-bare &&
+		echo "[includeIf \"worktree:/\"]path=bar-bare" >>config &&
+		echo "[test]wtbare=1" >bar-bare &&
+		test_must_fail git config test.wtbare
+	)
+'
+
+test_expect_success 'conditional include, worktree multiple worktrees' '
+	git init wt-multi &&
+	(
+		cd wt-multi &&
+		test_commit initial &&
+		git worktree add -b linked-branch ../wt-linked HEAD &&
+		git worktree add -b prefix-branch ../wt-prefix/linked HEAD
+	) &&
+	wt_main="$(cd wt-multi && pwd)" &&
+	wt_linked="$(cd wt-linked && pwd)" &&
+	wt_prefix_parent="$(cd wt-prefix && pwd)" &&
+	cat >>wt-multi/.git/config <<-EOF &&
+	[includeIf "worktree:$wt_main"]
+		path = main-config
+	[includeIf "worktree:$wt_linked"]
+		path = linked-config
+	[includeIf "worktree:$wt_prefix_parent/"]
+		path = prefix-config
+	EOF
+	echo "[test]mainvar=main" >wt-multi/.git/main-config &&
+	echo "[test]linkedvar=linked" >wt-multi/.git/linked-config &&
+	echo "[test]prefixvar=prefix" >wt-multi/.git/prefix-config &&
+	echo main >expect &&
+	git -C wt-multi config test.mainvar >actual &&
+	test_cmp expect actual &&
+	test_must_fail git -C wt-multi config test.linkedvar &&
+	test_must_fail git -C wt-multi config test.prefixvar &&
+	echo linked >expect &&
+	git -C wt-linked config test.linkedvar >actual &&
+	test_cmp expect actual &&
+	test_must_fail git -C wt-linked config test.mainvar &&
+	test_must_fail git -C wt-linked config test.prefixvar &&
+	echo prefix >expect &&
+	git -C wt-prefix/linked config test.prefixvar >actual &&
+	test_cmp expect actual &&
+	test_must_fail git -C wt-prefix/linked config test.mainvar &&
+	test_must_fail git -C wt-prefix/linked config test.linkedvar
+'
+
+test_expect_success SYMLINKS 'conditional include, worktree resolves symlinks' '
+	mkdir real-wt &&
+	ln -s real-wt link-wt &&
+	git init link-wt/repo &&
+	(
+		cd link-wt/repo &&
+		# repo->worktree resolves symlinks, so use real path in pattern
+		echo "[includeIf \"worktree:**/real-wt/repo\"]path=bar-link" >>.git/config &&
+		echo "[test]wtlink=2" >.git/bar-link &&
+		echo 2 >expect &&
+		git config test.wtlink >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done

diff --git a/Documentation/config.adoc b/Documentation/config.adoc
index 62eebe7c5450..a4f3ec905098 100644
--- a/Documentation/config.adoc
+++ b/Documentation/config.adoc
@@ -146,6 +146,48 @@ refer to linkgit:gitignore[5] for details. For convenience:
 	This is the same as `gitdir` except that matching is done
 	case-insensitively (e.g. on case-insensitive file systems)
 
+`worktree`::
+	The data that follows the keyword `worktree` and a colon is used as a
+	glob pattern. If the working directory of the current worktree matches
+	the pattern, the include condition is met.
++
+The worktree location is the path where files are checked out (as returned
+by `git rev-parse --show-toplevel`). This is different from `gitdir`, which
+matches the `.git` directory path. In a linked worktree, the worktree path
+is the directory where that worktree's files are located, not the main
+repository's `.git` directory.
++
+The pattern can contain standard globbing wildcards and two additional
+ones, `**/` and `/**`, that can match multiple path components. Please
+refer to linkgit:gitignore[5] for details. For convenience:
+
+ * If the pattern starts with `~/`, `~` will be substituted with the
+   content of the environment variable `HOME`.
+
+ * If the pattern starts with `./`, it is replaced with the directory
+   containing the current config file.
+
+ * If the pattern does not start with either `~/`, `./` or `/`, `**/`
+   will be automatically prepended. For example, the pattern `foo/bar`
+   becomes `**/foo/bar` and would match `/any/path/to/foo/bar`.
+
+ * If the pattern ends with `/`, `**` will be automatically added. For
+   example, the pattern `foo/` becomes `foo/**`. In other words, it
+   matches "foo" and everything inside, recursively.
++
+This condition will never match in a bare repository (which has no worktree).
++
+This is useful when you need to use different `user.name`, `user.email`, or
+GPG keys in different worktrees of the same repository. While
+`extensions.worktreeConfig` also allows per-worktree configuration, it
+requires changes inside each repository. This condition can be set in the
+user's global configuration file (e.g. `~/.config/git/config`) and applies
+to multiple repositories at once.
+
+`worktree/i`::
+	This is the same as `worktree` except that matching is done
+	case-insensitively (e.g. on case-insensitive file systems)
+
 `onbranch`::
 	The data that follows the keyword `onbranch` and a colon is taken to be a
 	pattern with standard globbing wildcards and two additional
@@ -244,6 +286,14 @@ Example
 [includeIf "gitdir:~/to/group/"]
 	path = /path/to/foo.inc
 
+; include if the worktree is at /path/to/project-build
+[includeIf "worktree:/path/to/project-build"]
+	path = build-config.inc
+
+; include for all worktrees inside /path/to/group
+[includeIf "worktree:/path/to/group/"]
+	path = group-config.inc
+
 ; relative paths are always relative to the including
 ; file (if the condition is true); their location is not
 ; affected by the condition

diff --git a/config.c b/config.c
index 156f2a24fa00..6d0c2d0725e4 100644
--- a/config.c
+++ b/config.c
@@ -235,23 +235,20 @@ static int prepare_include_condition_pattern(const struct key_value_info *kvi,
 	return 0;
 }
 
-static int include_by_gitdir(const struct key_value_info *kvi,
-			     const struct config_options *opts,
-			     const char *cond, size_t cond_len, int icase)
+static int include_by_path(const struct key_value_info *kvi,
+			   const char *path,
+			   const char *cond, size_t cond_len, int icase)
 {
 	struct strbuf text = STRBUF_INIT;
 	struct strbuf pattern = STRBUF_INIT;
 	size_t prefix;
 	int ret = 0;
-	const char *git_dir;
 	int already_tried_absolute = 0;
 
-	if (opts->git_dir)
-		git_dir = opts->git_dir;
-	else
+	if (!path)
 		goto done;
 
-	strbuf_realpath(&text, git_dir, 1);
+	strbuf_realpath(&text, path, 1);
 	strbuf_add(&pattern, cond, cond_len);
 	ret = prepare_include_condition_pattern(kvi, &pattern, &prefix);
 	if (ret < 0)
@@ -284,7 +281,7 @@ static int include_by_gitdir(const struct key_value_info *kvi,
 		 * which'll do the right thing
 		 */
 		strbuf_reset(&text);
-		strbuf_add_absolute_path(&text, git_dir);
+		strbuf_add_absolute_path(&text, path);
 		already_tried_absolute = 1;
 		goto again;
 	}
@@ -400,9 +397,15 @@ static int include_condition_is_true(const struct key_value_info *kvi,
 	const struct config_options *opts = inc->opts;
 
 	if (skip_prefix_mem(cond, cond_len, "gitdir:", &cond, &cond_len))
-		return include_by_gitdir(kvi, opts, cond, cond_len, 0);
+		return include_by_path(kvi, opts->git_dir, cond, cond_len, 0);
 	else if (skip_prefix_mem(cond, cond_len, "gitdir/i:", &cond, &cond_len))
-		return include_by_gitdir(kvi, opts, cond, cond_len, 1);
+		return include_by_path(kvi, opts->git_dir, cond, cond_len, 1);
+	else if (skip_prefix_mem(cond, cond_len, "worktree:", &cond, &cond_len))
+		return include_by_path(kvi, inc->repo ? repo_get_work_tree(inc->repo) : NULL,
+				       cond, cond_len, 0);
+	else if (skip_prefix_mem(cond, cond_len, "worktree/i:", &cond, &cond_len))
+		return include_by_path(kvi, inc->repo ? repo_get_work_tree(inc->repo) : NULL,
+				       cond, cond_len, 1);
 	else if (skip_prefix_mem(cond, cond_len, "onbranch:", &cond, &cond_len))
 		return include_by_branch(inc, cond, cond_len);
 	else if (skip_prefix_mem(cond, cond_len, "hasconfig:remote.*.url:", &cond,