diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index ac2818b9f66778..50759153ef15c7 100644
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -113,7 +113,13 @@ separated by an `=` (equals) sign, followed by a newline.
 The key may contain any bytes except `=`, newline, or NUL. The value may
 contain any bytes except newline or NUL.
 
-In both cases, all bytes are treated as-is (i.e., there is no quoting,
+Attributes with keys that end with C-style array brackets `[]` can have
+multiple values. Each instance of a multi-valued attribute forms an
+ordered list of values - the order of the repeated attributes defines
+the order of the values. An empty multi-valued attribute (`key[]=\n`)
+acts to clear any previous entries and reset the list.
+
+In all cases, all bytes are treated as-is (i.e., there is no quoting,
 and one cannot transmit a value with newline or NUL in it). The list of
 attributes is terminated by a blank line or end-of-file.
 
@@ -160,6 +166,17 @@ empty string.
 Components which are missing from the URL (e.g., there is no
 username in the example above) will be left unset.
 
+`wwwauth[]`::
+
+	When an HTTP response is received by Git that includes one or more
+	'WWW-Authenticate' authentication headers, these will be passed by Git
+	to credential helpers.
++
+Each 'WWW-Authenticate' header value is passed as a multi-valued
+attribute 'wwwauth[]', where the order of the attributes is the same as
+they appear in the HTTP response. This attribute is 'one-way' from Git
+to pass additional information to credential helpers.
+
 Unrecognised attributes are silently discarded.
 
 GIT
diff --git a/credential.c b/credential.c
index 897b4679333f9e..f566c8ab195c41 100644
--- a/credential.c
+++ b/credential.c
@@ -270,6 +270,9 @@ void credential_write(const struct credential *c, FILE *fp)
 	credential_write_item(fp, "path", c->path, 0);
 	credential_write_item(fp, "username", c->username, 0);
 	credential_write_item(fp, "password", c->password, 0);
+	for (size_t i = 0; i < c->wwwauth_headers.nr; i++)
+		credential_write_item(fp, "wwwauth[]", c->wwwauth_headers.v[i],
+				      0);
 }
 
 static int run_credential_helper(struct credential *c,
diff --git a/t/t5563-simple-http-auth.sh b/t/t5563-simple-http-auth.sh
index 40f1b381d1bcb7..64d2acd03280d5 100755
--- a/t/t5563-simple-http-auth.sh
+++ b/t/t5563-simple-http-auth.sh
@@ -69,6 +69,248 @@ test_expect_success 'access using basic auth' '
 	expect_credential_query get <<-EOF &&
 	protocol=http
 	host=$HTTPD_DEST
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=alice
+	password=secret-passwd
+	EOF
+'
+
+test_expect_success 'access using basic auth invalid credentials' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=baduser
+	password=wrong-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	cat >"$HTTPD_ROOT_PATH/custom-auth.challenge" <<-EOF &&
+	WWW-Authenticate: Basic realm="example.com"
+	EOF
+
+	test_config_global credential.helper test-helper &&
+	test_must_fail git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query erase <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=baduser
+	password=wrong-passwd
+	wwwauth[]=Basic realm="example.com"
+	EOF
+'
+
+test_expect_success 'access using basic auth with extra challenges' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=alice
+	password=secret-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	cat >"$HTTPD_ROOT_PATH/custom-auth.challenge" <<-EOF &&
+	WWW-Authenticate: FooBar param1="value1" param2="value2"
+	WWW-Authenticate: Bearer authorize_uri="id.example.com" p=1 q=0
+	WWW-Authenticate: Basic realm="example.com"
+	EOF
+
+	test_config_global credential.helper test-helper &&
+	git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=FooBar param1="value1" param2="value2"
+	wwwauth[]=Bearer authorize_uri="id.example.com" p=1 q=0
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=alice
+	password=secret-passwd
+	EOF
+'
+
+test_expect_success 'access using basic auth mixed-case wwwauth header name' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=alice
+	password=secret-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	cat >"$HTTPD_ROOT_PATH/custom-auth.challenge" <<-EOF &&
+	www-authenticate: foobar param1="value1" param2="value2"
+	WWW-AUTHENTICATE: BEARER authorize_uri="id.example.com" p=1 q=0
+	WwW-aUtHeNtIcAtE: baSiC realm="example.com"
+	EOF
+
+	test_config_global credential.helper test-helper &&
+	git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=foobar param1="value1" param2="value2"
+	wwwauth[]=BEARER authorize_uri="id.example.com" p=1 q=0
+	wwwauth[]=baSiC realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=alice
+	password=secret-passwd
+	EOF
+'
+
+test_expect_success 'access using basic auth with wwwauth header continuations' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=alice
+	password=secret-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	# Note that leading and trailing whitespace is important to correctly
+	# simulate a continuation/folded header.
+	cat >"$HTTPD_ROOT_PATH/custom-auth.challenge" <<-EOF &&
+	WWW-Authenticate: FooBar param1="value1"
+	 param2="value2"
+	WWW-Authenticate: Bearer authorize_uri="id.example.com"
+	 p=1
+	 q=0
+	WWW-Authenticate: Basic realm="example.com"
+	EOF
+
+	test_config_global credential.helper test-helper &&
+	git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=FooBar param1="value1" param2="value2"
+	wwwauth[]=Bearer authorize_uri="id.example.com" p=1 q=0
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=alice
+	password=secret-passwd
+	EOF
+'
+
+test_expect_success 'access using basic auth with wwwauth header empty continuations' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=alice
+	password=secret-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	CHALLENGE="$HTTPD_ROOT_PATH/custom-auth.challenge" &&
+
+	# Note that leading and trailing whitespace is important to correctly
+	# simulate a continuation/folded header.
+	printf "">$CHALLENGE &&
+	printf "WWW-Authenticate: FooBar param1=\"value1\"\r\n" >$CHALLENGE &&
+	printf " \r\n" >>$CHALLENGE &&
+	printf " param2=\"value2\"\r\n" >>$CHALLENGE &&
+	printf "WWW-Authenticate: Bearer authorize_uri=\"id.example.com\"\r\n" >>$CHALLENGE &&
+	printf " p=1\r\n" >>$CHALLENGE &&
+	printf " \r\n" >>$CHALLENGE &&
+	printf " q=0\r\n" >>$CHALLENGE &&
+	printf "WWW-Authenticate: Basic realm=\"example.com\"\r\n" >>$CHALLENGE &&
+
+	test_config_global credential.helper test-helper &&
+	git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=FooBar param1="value1" param2="value2"
+	wwwauth[]=Bearer authorize_uri="id.example.com" p=1 q=0
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	protocol=http
+	host=$HTTPD_DEST
+	username=alice
+	password=secret-passwd
+	EOF
+'
+
+test_expect_success 'access using basic auth with wwwauth header mixed line-endings' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	username=alice
+	password=secret-passwd
+	EOF
+
+	# Basic base64(alice:secret-passwd)
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	Basic YWxpY2U6c2VjcmV0LXBhc3N3ZA==
+	EOF
+
+	CHALLENGE="$HTTPD_ROOT_PATH/custom-auth.challenge" &&
+
+	# Note that leading and trailing whitespace is important to correctly
+	# simulate a continuation/folded header.
+	printf "">$CHALLENGE &&
+	printf "WWW-Authenticate: FooBar param1=\"value1\"\r\n" >$CHALLENGE &&
+	printf " \r\n" >>$CHALLENGE &&
+	printf "\tparam2=\"value2\"\r\n" >>$CHALLENGE &&
+	printf "WWW-Authenticate: Basic realm=\"example.com\"" >>$CHALLENGE &&
+
+	test_config_global credential.helper test-helper &&
+	git ls-remote "$HTTPD_URL/custom_auth/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	protocol=http
+	host=$HTTPD_DEST
+	wwwauth[]=FooBar param1="value1" param2="value2"
+	wwwauth[]=Basic realm="example.com"
 	EOF
 
 	expect_credential_query store <<-EOF