diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt
index 5a60bbfa7f4..acfd5dc1d8b 100644
--- a/Documentation/technical/api-parse-options.txt
+++ b/Documentation/technical/api-parse-options.txt
@@ -198,11 +198,6 @@ There are some macros to easily define options:
 	The filename will be prefixed by passing the filename along with
 	the prefix argument of `parse_options()` to `prefix_filename()`.
 
-`OPT_ARGUMENT(long, &int_var, description)`::
-	Introduce a long-option argument that will be kept in `argv[]`.
-	If this option was seen, `int_var` will be set to one (except
-	if a `NULL` pointer was passed).
-
 `OPT_NUMBER_CALLBACK(&var, description, func_ptr)`::
 	Recognize numerical options like -123 and feed the integer as
 	if it was an argument to the function given by `func_ptr`.
diff --git a/builtin/difftool.c b/builtin/difftool.c
index de2e5545c81..bb9fe7245a4 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -709,7 +709,7 @@ int cmd_difftool(int argc, const char **argv, const char *prefix)
 			    "tool returns a non - zero exit code")),
 		OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 			   N_("specify a custom command for viewing diffs")),
-		OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
+		OPT_BOOL(0, "no-index", &no_index, N_("passed to `diff`")),
 		OPT_END()
 	};
 	struct child_process child = CHILD_PROCESS_INIT;
@@ -763,6 +763,8 @@ int cmd_difftool(int argc, const char **argv, const char *prefix)
 	 * each file that changed.
 	 */
 	strvec_push(&child.args, "diff");
+	if (no_index)
+		strvec_push(&child.args, "--no-index");
 	if (dir_diff)
 		strvec_pushl(&child.args, "--raw", "--no-abbrev", "-z", NULL);
 	strvec_pushv(&child.args, argv);
diff --git a/parse-options.c b/parse-options.c
index 2abff136a17..55c5821b08d 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -310,19 +310,6 @@ static enum parse_opt_result parse_long_opt(
 again:
 		if (!skip_prefix(arg, long_name, &rest))
 			rest = NULL;
-		if (options->type == OPTION_ARGUMENT) {
-			if (!rest)
-				continue;
-			if (*rest == '=')
-				return error(_("%s takes no value"),
-					     optname(options, flags));
-			if (*rest)
-				continue;
-			if (options->value)
-				*(int *)options->value = options->defval;
-			p->out[p->cpidx++] = arg - 2;
-			return PARSE_OPT_DONE;
-		}
 		if (!rest) {
 			/* abbreviated? */
 			if (!(p->flags & PARSE_OPT_KEEP_UNKNOWN) &&
diff --git a/parse-options.h b/parse-options.h
index a845a9d9527..39d90882548 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -8,7 +8,6 @@
 enum parse_opt_type {
 	/* special types */
 	OPTION_END,
-	OPTION_ARGUMENT,
 	OPTION_GROUP,
 	OPTION_NUMBER,
 	OPTION_ALIAS,
@@ -155,8 +154,6 @@ struct option {
 #define OPT_INTEGER_F(s, l, v, h, f)     { OPTION_INTEGER, (s), (l), (v), N_("n"), (h), (f) }
 
 #define OPT_END()                   { OPTION_END }
-#define OPT_ARGUMENT(l, v, h)       { OPTION_ARGUMENT, 0, (l), (v), NULL, \
-				      (h), PARSE_OPT_NOARG, NULL, 1 }
 #define OPT_GROUP(h)                { OPTION_GROUP, 0, NULL, NULL, NULL, (h) }
 #define OPT_BIT(s, l, v, h, b)      OPT_BIT_F(s, l, v, h, b, 0)
 #define OPT_BITOP(s, l, v, h, set, clear) { OPTION_BITOP, (s), (l), (v), NULL, (h), \
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index 2051ce57db7..a282b6ff13e 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -134,7 +134,6 @@ int cmd__parse_options(int argc, const char **argv)
 		OPT_NOOP_NOARG(0, "obsolete"),
 		OPT_STRING_LIST(0, "list", &list, "str", "add str to list"),
 		OPT_GROUP("Magic arguments"),
-		OPT_ARGUMENT("quux", NULL, "means --quux"),
 		OPT_NUMBER_CALLBACK(&integer, "set integer to NUM",
 			number_callback),
 		{ OPTION_COUNTUP, '+', NULL, &boolean, NULL, "same as -b",
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index ad4746d899a..da310ed29b1 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -37,7 +37,6 @@ String options
     --list <str>          add str to list
 
 Magic arguments
-    --quux                means --quux
     -NUM                  set integer to NUM
     +                     same as -b
     --ambiguous           positive ambiguity
@@ -263,10 +262,6 @@ test_expect_success 'detect possible typos' '
 	test_cmp typo.err output.err
 '
 
-test_expect_success 'keep some options as arguments' '
-	test-tool parse-options --expect="arg 00: --quux" --quux
-'
-
 cat >expect <<\EOF
 Callback: "four", 0
 boolean: 5
