diff --git a/src/Symfony/Component/Validator/Constraints/Url.php b/src/Symfony/Component/Validator/Constraints/Url.php
index 3306c1b405561..3c36d72f76492 100644
--- a/src/Symfony/Component/Validator/Constraints/Url.php
+++ b/src/Symfony/Component/Validator/Constraints/Url.php
@@ -104,6 +104,7 @@ class Url extends Constraint
      * @deprecated since Symfony 4.1, to be removed in 5.0
      */
     public $checkDNS = self::CHECK_DNS_TYPE_NONE;
+    public $relativeProtocol = false;
 
     public function __construct($options = null)
     {
diff --git a/src/Symfony/Component/Validator/Constraints/UrlValidator.php b/src/Symfony/Component/Validator/Constraints/UrlValidator.php
index 932aa14436fbc..8490d5c10e74f 100644
--- a/src/Symfony/Component/Validator/Constraints/UrlValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/UrlValidator.php
@@ -61,7 +61,8 @@ public function validate($value, Constraint $constraint)
             return;
         }
 
-        $pattern = sprintf(static::PATTERN, implode('|', $constraint->protocols));
+        $pattern = $constraint->relativeProtocol ? str_replace('(%s):', '(?:(%s):)?', static::PATTERN) : static::PATTERN;
+        $pattern = sprintf($pattern, implode('|', $constraint->protocols));
 
         if (!preg_match($pattern, $value)) {
             $this->context->buildViolation($constraint->message)
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php
index b7c1dc1d776a7..87b3f0d10ef70 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php
@@ -65,6 +65,30 @@ public function testValidUrls($url)
         $this->assertNoViolation();
     }
 
+    /**
+     * @dataProvider getValidRelativeUrls
+     * @dataProvider getValidUrls
+     */
+    public function testValidRelativeUrl($url)
+    {
+        $constraint = new Url(array(
+            'relativeProtocol' => true,
+        ));
+
+        $this->validator->validate($url, $constraint);
+
+        $this->assertNoViolation();
+    }
+
+    public function getValidRelativeUrls()
+    {
+        return array(
+            array('//google.com'),
+            array('//symfony.fake/blog/'),
+            array('//symfony.com/search?type=&q=url+validator'),
+        );
+    }
+
     public function getValidUrls()
     {
         return array(
@@ -147,6 +171,46 @@ public function testInvalidUrls($url)
             ->assertRaised();
     }
 
+    /**
+     * @dataProvider getInvalidRelativeUrls
+     * @dataProvider getInvalidUrls
+     */
+    public function testInvalidRelativeUrl($url)
+    {
+        $constraint = new Url(array(
+            'message' => 'myMessage',
+            'relativeProtocol' => true,
+        ));
+
+        $this->validator->validate($url, $constraint);
+
+        $this->buildViolation('myMessage')
+            ->setParameter('{{ value }}', '"'.$url.'"')
+            ->setCode(Url::INVALID_URL_ERROR)
+            ->assertRaised();
+    }
+
+    public function getInvalidRelativeUrls()
+    {
+        return array(
+            array('/google.com'),
+            array('//goog_le.com'),
+            array('//google.com::aa'),
+            array('//google.com:aa'),
+            array('//127.0.0.1:aa/'),
+            array('//[::1'),
+            array('//hello.☎/'),
+            array('//:password@symfony.com'),
+            array('//:password@@symfony.com'),
+            array('//username:passwordsymfony.com'),
+            array('//usern@me:password@symfony.com'),
+            array('//example.com/exploit.html?<script>alert(1);</script>'),
+            array('//example.com/exploit.html?hel lo'),
+            array('//example.com/exploit.html?not_a%hex'),
+            array('//'),
+        );
+    }
+
     public function getInvalidUrls()
     {
         return array(