diff --git a/core/lib/Drupal/Core/Url.php b/core/lib/Drupal/Core/Url.php
index 4ee3692..0511193 100644
--- a/core/lib/Drupal/Core/Url.php
+++ b/core/lib/Drupal/Core/Url.php
@@ -32,7 +32,7 @@ class Url {
    *
    * @var \Drupal\Core\Utility\UnroutedUrlAssemblerInterface
    */
-  protected $urlAssember;
+  protected $urlAssembler;
 
   /**
    * The access manager
@@ -116,10 +116,66 @@ public function __construct($route_name, $route_parameters = array(), $options =
     $this->options = $options;
   }
 
+  /**
+   * Creates a new routed (internal to Drupal) URL object.
+   *
+   * @param string $route_name
+   *   The name of the route
+   * @param array $route_parameters
+   *   (optional) An associative array of parameter names and values.
+   * @param array $options
+   *   (optional) An associative array of additional 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.
+   *   - '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
+   *     absolute link (beginning with http:). Useful for links that will be
+   *     displayed outside the site, such as in an RSS feed.
+   *   - 'language': An optional language object used to look up the alias
+   *     for the URL. If $options['language'] is omitted, it defaults to the
+   *     current language for the language type LanguageInterface::TYPE_URL.
+   *   - 'https': Whether this URL should point to a secure location. If not
+   *     defined, the current scheme is used, so the user stays on HTTP or HTTPS
+   *     respectively. if mixed mode sessions are permitted, TRUE enforces HTTPS
+   *     and FALSE enforces HTTP.
+   *
+   * @return \Drupal\Core\Url
+   *   A new routed (internal to Drupal) URL object.
+   */
   public static function routed($route_name, $route_parameters = array(), $options = array()) {
     return new static($route_name, $route_parameters, $options);
   }
 
+  /**
+   * Creates a new unrouted (external to Drupal) URL object.
+   *
+   * @param string $uri
+   *   The URI of the external resource including the scheme. For Drupal paths
+   *   that are not handled by the routing system, you may use base:// for the
+   *   scheme.
+   * @param array $options
+   *   (optional) An associative array of additional 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.
+   *   - '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
+   *     absolute link (beginning with http:). Useful for links that will be
+   *     displayed outside the site, such as in an RSS feed.
+   *   - 'language': An optional language object used to look up the alias
+   *     for the URL. If $options['language'] is omitted, it defaults to the
+   *     current language for the language type LanguageInterface::TYPE_URL.
+   *   - 'https': Whether this URL should point to a secure location. If not
+   *     defined, the current scheme is used, so the user stays on HTTP or HTTPS
+   *     respectively. if mixed mode sessions are permitted, TRUE enforces HTTPS
+   *     and FALSE enforces HTTP.
+   *
+   * @return \Drupal\Core\Url
+   *   A new unrouted (external to Drupal) URL object.
+   */
   public static function unrouted($uri, $options = array()) {
     $url = new static($uri, array(), $options);
     $url->setUnrouted();
@@ -169,7 +225,9 @@ protected function setUnrouted() {
     // Set empty route name and parameters.
     $this->routeName = NULL;
     $this->routeParameters = array();
-    $this->external = strpos($this->uri, 'base://') !== 0;
+    if ($this->external = strpos($this->uri, 'base://') !== 0) {
+      $this->options['external'] = TRUE;
+    }
   }
 
   /**
@@ -475,10 +533,10 @@ protected function urlGenerator() {
    *   The URL builder.
    */
   protected function unroutedUrlAssembler() {
-    if (!$this->urlAssember) {
-      $this->urlAssember = \Drupal::service('unrouted_url_assembler');
+    if (!$this->urlAssembler) {
+      $this->urlAssembler = \Drupal::service('unrouted_url_assembler');
     }
-    return $this->urlAssember;
+    return $this->urlAssembler;
   }
 
   /**
@@ -503,7 +561,7 @@ public function setUrlGenerator(UrlGeneratorInterface $url_generator) {
    * @return $this
    */
   public function setUnroutedUrlAssembler(UnroutedUrlAssemblerInterface $url_assembler) {
-    $this->urlAssember = $url_assembler;
+    $this->urlAssembler = $url_assembler;
     return $this;
   }
 
diff --git a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
index f1d179f..a23972f 100644
--- a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
+++ b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
@@ -13,6 +13,7 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
 use Drupal\link\LinkItemInterface;
+use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Plugin implementation of the 'link' formatter.
@@ -206,7 +207,18 @@ protected function buildUrl(LinkItemInterface $item) {
     }
 
     if ($item->isExternal()) {
-      $url = Url::unrouted($item->url, $options);
+      // @todo LinkItemInterface shouldn't treat items with no scheme as
+      //   external, including <front>.
+      if (parse_url($item->url, PHP_URL_SCHEME)) {
+        $url = Url::unrouted($item->url, $options);
+      }
+      elseif ($item->url == '<front>') {
+        $url = new Url('<front>');
+      }
+      else {
+        // No base path - assume internal.
+        $url = Url::createFromRequest(Request::create('/' . ltrim($item->url, '/')));
+      }
     }
     else {
       $url = Url::routed($item->route_name, (array) $item->route_parameters, (array) $options);
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 65b4b04..71ecd5e 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -576,6 +576,7 @@ function template_preprocess_username(&$variables) {
   $variables['name'] = String::checkPlain($name);
   $variables['profile_access'] = \Drupal::currentUser()->hasPermission('access user profiles');
 
+  $external = FALSE;
   // Populate link path and attributes if appropriate.
   if ($variables['uid'] && $variables['profile_access']) {
     // We are linking to a local user.
@@ -589,10 +590,19 @@ function template_preprocess_username(&$variables) {
     $variables['attributes']['rel'] = 'nofollow';
     $variables['link_path'] = $account->homepage;
     $variables['homepage'] = $account->homepage;
+    $external = TRUE;
   }
   // We have a link path, so we should generate a URL.
   if (isset($variables['link_path'])) {
-    $variables['attributes']['href'] = \Drupal::service('unrouted_url_assembler')->assemble($variables['link_path'], $variables['link_options']);
+    if ($external) {
+      $variables['attributes']['href'] = \Drupal::service('unrouted_url_assembler')
+        ->assemble($variables['link_path'], $variables['link_options']);
+    }
+    else {
+      $variables['attributes']['href'] = Url::routed('entity.user.canonical', array(
+        'user' => $variables['uid'],
+      ))->toString();
+    }
   }
 }
 
diff --git a/core/tests/Drupal/Tests/Core/UrlTest.php b/core/tests/Drupal/Tests/Core/UrlTest.php
index 4f5108f..7cc514a 100644
--- a/core/tests/Drupal/Tests/Core/UrlTest.php
+++ b/core/tests/Drupal/Tests/Core/UrlTest.php
@@ -103,7 +103,7 @@ public function testCreateFromPath() {
     $urls = array();
     foreach ($this->map as $index => $values) {
       $path = array_pop($values);
-      $url = Url::createFromRequest(Request::create("/$path"));
+      $url = Url::createFromRequest(Request::create("$path"));
       $this->assertSame($values, array_values($url->toArray()));
       $urls[$index] = $url;
     }
@@ -209,6 +209,9 @@ public function testIsExternal($urls) {
   /**
    * Tests the getPath() method for internal URLs.
    *
+   * @param \Drupal\Core\Url[] $urls
+   *   Array of URL objects.
+   *
    * @depends testCreateFromPath
    *
    * @expectedException \UnexpectedValueException
@@ -217,7 +220,7 @@ public function testIsExternal($urls) {
    */
   public function testGetPathForInternalUrl($urls) {
     foreach ($urls as $url) {
-      $url->getPath();
+      $url->getUri();
     }
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php b/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php
index 72dd40b..8c38e75 100644
--- a/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php
+++ b/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php
@@ -40,6 +40,13 @@ class LinkGeneratorTest extends UnitTestCase {
   protected $moduleHandler;
 
   /**
+   * The mocked URL Assembler service.
+   *
+   * @var \PHPUnit_Framework_MockObject_MockObject|\Drupal\Core\Utility\UnroutedUrlAssemblerInterface
+   */
+  protected $urlAssembler;
+
+  /**
    * Contains the LinkGenerator default options.
    */
   protected $defaultOptions = array(
@@ -60,6 +67,7 @@ protected function setUp() {
     $this->moduleHandler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
 
     $this->linkGenerator = new LinkGenerator($this->urlGenerator, $this->moduleHandler);
+    $this->urlAssembler = $this->getMock('\Drupal\Core\Utility\UnroutedUrlAssemblerInterface');
   }
 
   /**
@@ -142,17 +150,18 @@ public function testGenerateFromUrl() {
    * @covers ::generateFromUrl()
    */
   public function testGenerateFromUrlExternal() {
-    $this->urlGenerator->expects($this->once())
-      ->method('generateFromPath')
-      ->with('http://drupal.org', array('set_active_class' => TRUE, 'external' => TRUE) + $this->defaultOptions)
-      ->will($this->returnArgument(0));
-
     $this->moduleHandler->expects($this->once())
       ->method('alter')
       ->with('link', $this->isType('array'));
 
+    $this->urlAssembler->expects($this->once())
+      ->method('assemble')
+      ->with('http://drupal.org', array('set_active_class' => TRUE, 'external' => TRUE) + $this->defaultOptions)
+      ->willReturnArgument(0);
+
     $url = Url::unrouted('http://drupal.org');
     $url->setUrlGenerator($this->urlGenerator);
+    $url->setUnroutedUrlAssembler($this->urlAssembler);
     $url->setOption('set_active_class', TRUE);
 
     $result = $this->linkGenerator->generateFromUrl('Drupal', $url);