diff --git a/core/lib/Drupal/Core/Url.php b/core/lib/Drupal/Core/Url.php
index b2e2b86..70e0461 100644
--- a/core/lib/Drupal/Core/Url.php
+++ b/core/lib/Drupal/Core/Url.php
@@ -252,20 +252,22 @@ public static function fromUri($uri, $options = []) {
     $uri_parts += ['path' => '', 'fragment' => ''];
     // Extract query parameters and fragment and merge them into $options.
     $options += ['fragment' => $uri_parts['fragment']];
+    unset($uri_parts['fragment']);
     if (!empty($uri_parts['query'])) {
       $uri_query = [];
       parse_str($uri_parts['query'], $uri_query);
       $options['query'] += $uri_query;
+      unset($uri_parts['query']);
     }
 
     if ($uri_parts['scheme'] === 'entity') {
-      $url = static::fromEntityUri($uri, $options);
+      $url = static::fromEntityUri($uri_parts, $options);
     }
     elseif ($uri_parts['scheme'] === 'user-path') {
-      $url = static::fromUserPathUri($uri, $options);
+      $url = static::fromUserPathUri($uri_parts, $options);
     }
     elseif ($uri_parts['scheme'] === 'route') {
-      $url = static::fromRouteUri($uri, $options);
+      $url = static::fromRouteUri($uri_parts, $options);
     }
     else {
       $url = new static($uri, array(), $options);
@@ -282,8 +284,8 @@ public static function fromUri($uri, $options = []) {
   /**
    * Create a new Url object for entity URIs.
    *
-   * @param string $uri
-   *   An URI of the form entity:{entity_type}/{entity_id}.
+   * @param array $uri_parts
+   *   Parts from an URI of the form entity:{entity_type}/{entity_id}.
    * @param array $options
    *   An array of options, see static::fromUri() for details.
    *
@@ -293,8 +295,7 @@ public static function fromUri($uri, $options = []) {
    * @throws \InvalidArgumentException
    *   Thrown if the entity URI is invalid.
    */
-  protected static function fromEntityUri($uri, $options) {
-    $uri_parts = parse_url($uri);
+  protected static function fromEntityUri(array $uri_parts, $options) {
     list($entity_type_id, $entity_id) = explode('/', $uri_parts['path'], 2);
     if ($uri_parts['scheme'] != 'entity' || $entity_id === '') {
       throw new \InvalidArgumentException(String::format('The entity URI "@uri" is invalid. You must specify the entity id in the URL. e.g., entity:node/1 for loading the canonical path to node entity with id 1.', ['@uri' => $uri]));
@@ -306,16 +307,15 @@ protected static function fromEntityUri($uri, $options) {
   /**
    * Creates a new Url object for 'user-path:' URIs.
    *
-   * @param string $uri
-   *   An URI of the form user-path:{path}.
+   * @param array $uri_parts
+   *   Parts from an URI of the form user-path:{path}.
    * @param array $options
    *   An array of options, see static::fromUri() for details.
    *
    * @return \Drupal\Core\Url
    *   A new Url object for a 'user-path:' URI.
    */
-  protected static function fromUserPathUri($uri, array $options) {
-    $uri_parts = parse_url($uri);
+  protected static function fromUserPathUri(array $uri_parts, array $options) {
     $url = \Drupal::pathValidator()
       ->getUrlIfValidWithoutAccessCheck($uri_parts['path']) ?: static::fromUri('base:' . $uri_parts['path'], $options);
     // Allow specifying additional options.
@@ -327,18 +327,17 @@ protected static function fromUserPathUri($uri, array $options) {
   /**
    * Creates a new Url object for 'route:' URIs.
    *
-   * @param string $uri
-   *   An URI of the form route:{path}. Where path is the route name optionally
-   *   followed by a ";" followed by query parameters in key=value format
-   *   with & separators.
+   * @param array $uri_parts
+   *   Parts from an URI of the form route:{path}. Where path is the route name
+   *   optionally followed by a ";" followed by query parameters in key=value
+   *   format with & separators.
    * @param array $options
    *   An array of options, see static::fromUri() for details.
    *
    * @return \Drupal\Core\Url
    *   A new Url object for a 'route:' URI.
    */
-  protected static function fromRouteUri($uri, array $options) {
-    $uri_parts = parse_url($uri);
+  protected static function fromRouteUri(array $uri_parts, array $options) {
     $route_parts = explode(';', $uri_parts['path'], 2);
     $route_name = $route_parts[0];
     $route_parameters = [];
diff --git a/core/tests/Drupal/Tests/Core/UrlTest.php b/core/tests/Drupal/Tests/Core/UrlTest.php
index a6a9a6c..9c5efcb 100644
--- a/core/tests/Drupal/Tests/Core/UrlTest.php
+++ b/core/tests/Drupal/Tests/Core/UrlTest.php
@@ -520,13 +520,52 @@ public function testInvalidEntityUriParameter() {
   }
 
   /**
-   * Tests the fromUri() method with an entity: URI.
+   * Tests the toUriString() method with entity: URI.
    *
-   * @covers ::fromUri
+   * @covers ::toUriString
    */
-  public function testToUriString() {
+  public function testToUriStringForEntity() {
     $url = Url::fromUri('entity:test_entity/1');
     $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1');
+    $url = Url::fromUri('entity:test_entity/1', ['fragment' => 'top', 'query' => ['page' => '2']]);
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
+    $url = Url::fromUri('entity:test_entity/1?page=2#top');
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
+  }
+
+  /**
+   * Tests the toUriString() method with user-path: URI.
+   *
+   * @covers ::toUriString
+   */
+  public function testToUriStringForUserPath() {
+    $url = Url::fromRoute('entity.test_entity.canonical', ['test_entity' => '1']);
+    $this->pathValidator->expects($this->any())
+      ->method('getUrlIfValidWithoutAccessCheck')
+      ->with('test-entity/1')
+      ->willReturn($url);
+    $url = Url::fromUri('user-path:test-entity/1');
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1');
+    $url = Url::fromUri('user-path:test-entity/1', ['fragment' => 'top']);
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1#top');
+    $url = Url::fromUri('user-path:test-entity/1', ['fragment' => 'top', 'query' => ['page' => '2']]);
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
+    $url = Url::fromUri('user-path:test-entity/1?page=2#top');
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
+  }
+
+  /**
+   * Tests the toUriString() method with route: URI.
+   *
+   * @covers ::toUriString
+   */
+  public function testToUriStringForRoute() {
+    $url = Url::fromUri('route:entity.test_entity.canonical;test_entity=1');
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1');
+    $url = Url::fromUri('route:entity.test_entity.canonical;test_entity=1', ['fragment' => 'top', 'query' => ['page' => '2']]);
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
+    $url = Url::fromUri('route:entity.test_entity.canonical;test_entity=1?page=2#top');
+    $this->assertSame($url->toUriString(), 'route:entity.test_entity.canonical;test_entity=1?page=2#top');
   }
 
   /**