diff --git a/core/lib/Drupal/Core/Url.php b/core/lib/Drupal/Core/Url.php
index 70e0461..7125bc1 100644
--- a/core/lib/Drupal/Core/Url.php
+++ b/core/lib/Drupal/Core/Url.php
@@ -214,7 +214,7 @@ public static function fromRouteMatch(RouteMatchInterface $route_match) {
    *   (optional) An associative array of additional URL options, with the
    *   following elements:
    *   - 'query': An array of query key/value-pairs (without any URL-encoding)
-   *     to append to the URL. Merged with the parameters array.
+   *     to append to the URL.
    *   - 'fragment': A fragment identifier (named anchor) to append to the URL.
    *     Do not include the leading '#' character.
    *   - 'absolute': Defaults to FALSE. Whether to force the output to be an
@@ -247,27 +247,30 @@ public static function fromUri($uri, $options = []) {
       throw new \InvalidArgumentException(String::format('The URI "@uri" is malformed.', ['@uri' => $uri]));
     }
     if (empty($uri_parts['scheme'])) {
-      throw new \InvalidArgumentException(String::format('The URI "@uri" is invalid. You must use a valid URI scheme. Use base: for items like a static file that needs the base path. Use user-path: for user input without a scheme. Use entity: for referencing the canonical route of a content entity.', ['@uri' => $uri]));
+      throw new \InvalidArgumentException(String::format('The URI "@uri" is invalid. You must use a valid URI scheme. Use base: for items like a static file that needs the base path. Use user-path: for user input without a scheme. Use entity: for referencing the canonical route of a content entity. Use route: for directly representing a route name and parameters.', ['@uri' => $uri]));
+    }
+    $uri_parts += ['path' => ''];
+    // Extract query parameters and fragment and merge them into $uri_options,
+    // but preserve the original $options for the fallback case.
+    if (!empty($uri_parts['fragment'])) {
+      $uri_options = $options + ['fragment' => $uri_parts['fragment']];
     }
-    $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;
+      $uri_options['query'] = isset($uri_options['query']) ? $uri_options['query'] + $uri_query : $uri_query;
       unset($uri_parts['query']);
     }
 
     if ($uri_parts['scheme'] === 'entity') {
-      $url = static::fromEntityUri($uri_parts, $options);
+      $url = static::fromEntityUri($uri_parts, $uri_options, $uri);
     }
     elseif ($uri_parts['scheme'] === 'user-path') {
-      $url = static::fromUserPathUri($uri_parts, $options);
+      $url = static::fromUserPathUri($uri_parts, $uri_options);
     }
     elseif ($uri_parts['scheme'] === 'route') {
-      $url = static::fromRouteUri($uri_parts, $options);
+      $url = static::fromRouteUri($uri_parts, $uri_options, $uri);
     }
     else {
       $url = new static($uri, array(), $options);
@@ -285,7 +288,8 @@ public static function fromUri($uri, $options = []) {
    * Create a new Url object for entity URIs.
    *
    * @param array $uri_parts
-   *   Parts from an URI of the form entity:{entity_type}/{entity_id}.
+   *   Parts from an URI of the form entity:{entity_type}/{entity_id} as from
+   *   parse_url().
    * @param array $options
    *   An array of options, see static::fromUri() for details.
    *
@@ -295,7 +299,7 @@ public static function fromUri($uri, $options = []) {
    * @throws \InvalidArgumentException
    *   Thrown if the entity URI is invalid.
    */
-  protected static function fromEntityUri(array $uri_parts, $options) {
+  protected static function fromEntityUri(array $uri_parts, $options, $uri) {
     list($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]));
@@ -308,7 +312,7 @@ protected static function fromEntityUri(array $uri_parts, $options) {
    * Creates a new Url object for 'user-path:' URIs.
    *
    * @param array $uri_parts
-   *   Parts from an URI of the form user-path:{path}.
+   *   Parts from an URI of the form user-path:{path}  as from parse_url().
    * @param array $options
    *   An array of options, see static::fromUri() for details.
    *
@@ -328,18 +332,21 @@ protected static function fromUserPathUri(array $uri_parts, array $options) {
    * Creates a new Url object for 'route:' URIs.
    *
    * @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.
+   *   Parts from an URI of the form route:{path}  as from parse_url(). Where
+   *   path is the route name optionally followed by a ";" followed by route
+   *   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(array $uri_parts, array $options) {
+  protected static function fromRouteUri(array $uri_parts, array $options, $uri) {
     $route_parts = explode(';', $uri_parts['path'], 2);
     $route_name = $route_parts[0];
+    if ($route_name === '') {
+      throw new \InvalidArgumentException(String::format('The route URI "@uri" is invalid. You must have a route name in the URI. e.g., route:system.admin', ['@uri' => $uri]));
+    }
     $route_parameters = [];
     if (!empty($route_parts[1])) {
       parse_str($route_parts[1], $route_parameters);
diff --git a/core/modules/system/src/Tests/Common/UrlTest.php b/core/modules/system/src/Tests/Common/UrlTest.php
index 45ae2d3..0b8a223 100644
--- a/core/modules/system/src/Tests/Common/UrlTest.php
+++ b/core/modules/system/src/Tests/Common/UrlTest.php
@@ -265,7 +265,7 @@ function testExternalUrls() {
     // Verify external URL can contain a query string.
     $url = $test_url . '?drupal=awesome';
     $result = Url::fromUri($url)->toString();
-    $this->assertEqual($url, $result, 'External URL with query string works without a query string in $options.');
+    $this->assertEqual($url, $result);
 
     // Verify external URL can be extended with a query string.
     $url = $test_url;
@@ -277,6 +277,6 @@ function testExternalUrls() {
     $url = $test_url . '?drupal=awesome';
     $query = array($this->randomMachineName(5) => $this->randomMachineName(5));
     $result = Url::fromUri($url, array('query' => $query))->toString();
-    $this->assertEqual($url . '&' . http_build_query($query, '', '&'), $result, 'External URL query string can be extended with a custom query string in $options.');
+    $this->assertEqual($url . '&' . http_build_query($query, '', '&'), $result);
   }
 }
diff --git a/core/tests/Drupal/Tests/Core/UrlTest.php b/core/tests/Drupal/Tests/Core/UrlTest.php
index 9c5efcb..6e2634b 100644
--- a/core/tests/Drupal/Tests/Core/UrlTest.php
+++ b/core/tests/Drupal/Tests/Core/UrlTest.php
@@ -520,7 +520,7 @@ public function testInvalidEntityUriParameter() {
   }
 
   /**
-   * Tests the toUriString() method with entity: URI.
+   * Tests the toUriString() method with entity: URIs.
    *
    * @covers ::toUriString
    */
@@ -534,7 +534,7 @@ public function testToUriStringForEntity() {
   }
 
   /**
-   * Tests the toUriString() method with user-path: URI.
+   * Tests the toUriString() method with user-path: URIs.
    *
    * @covers ::toUriString
    */
@@ -555,7 +555,7 @@ public function testToUriStringForUserPath() {
   }
 
   /**
-   * Tests the toUriString() method with route: URI.
+   * Tests the toUriString() method with route: URIs.
    *
    * @covers ::toUriString
    */