diff --git a/core/default.settings.php b/core/default.settings.php
index 0de6589..ab603d0 100644
--- a/core/default.settings.php
+++ b/core/default.settings.php
@@ -45,8 +45,6 @@
  * hostname with that number. For example,
  * http://www.drupal.org:8080/mysite/test/ could be loaded from
  * sites/8080.www.drupal.org.mysite.test/.
- *
- * @see \Drupal\Core\Utility\Site::getPath()
  */
 
 /**
@@ -66,16 +64,16 @@
  * the database (files, system table, etc.) this will ensure the paths are
  * correct when the site is deployed to a live server.
  *
- * Aliases are defined in an associative array in the format:
+ * Aliases are defined in an associative array named $sites. The array is
+ * written in the format: '<port>.<domain>.<path>' => 'directory'. As an
+ * example, to map http://www.drupal.org:8080/mysite/test to the configuration
+ * directory sites/example.com, the array should be defined as:
  * @code
- *   '<port>.<domain>.<path>' => 'directory',
- * @endcode
- * For example, to map http://www.drupal.org:8080/mysite/test to the directory
- * sites/example.com, the array should be defined as:
- * @code
- * $sites['8080.www.drupal.org.mysite.test'] = 'example.com';
+ * $sites = array(
+ *   '8080.www.drupal.org.mysite.test' => 'example.com',
+ * );
  * @endcode
- * The URL http://www.drupal.org:8080/mysite/test/ could be a symbolic link or
+ * The URL, http://www.drupal.org:8080/mysite/test/, could be a symbolic link or
  * an Apache Alias directive that points to the Drupal root containing
  * index.php. An alias could also be created for a subdomain. See the
  * @link http://drupal.org/documentation/install online Drupal installation guide @endlink
@@ -83,16 +81,21 @@
  *
  * The following examples look for a site configuration in sites/example.com:
  * @code
- * # URL: http://dev.drupal.org
+ * URL: http://dev.drupal.org
  * $sites['dev.drupal.org'] = 'example.com';
- * # URL: http://localhost/example
+ *
+ * URL: http://localhost/example
  * $sites['localhost.example'] = 'example.com';
- * # URL: http://localhost:8080/example
+ *
+ * URL: http://localhost:8080/example
  * $sites['8080.localhost.example'] = 'example.com';
- * # URL: http://www.drupal.org:8080/mysite/test/
+ *
+ * URL: http://www.drupal.org:8080/mysite/test/
  * $sites['8080.www.drupal.org.mysite.test'] = 'example.com';
  * @endcode
  *
+ * @see default.settings.php
+ * @see \Drupal\Core\Utility\Site::getPath()
  * @see http://drupal.org/documentation/install/multi-site
  */
 # $sites = array();
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 2d227c8..58187d3 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -248,36 +248,6 @@ function timer_stop($name) {
 }
 
 /**
- * Returns the appropriate configuration directory.
- *
- * @param string $custom_path
- *   (optional) A custom $conf_path to set and statically cache.
- * @param bool $reset
- *   Force a full search for matching directories even if one had been
- *   found previously. Defaults to FALSE.
- *
- * @deprecated Use \Drupal\Core\Utility\Site::getPath() instead.
- */
-function conf_path($custom_path = NULL, $reset = FALSE) {
-  if (!empty($custom_path) && is_string($custom_path)) {
-    Site::setPath($custom_path);
-  }
-  if ($reset) {
-    Site::reset();
-  }
-  return Site::getPath();
-}
-
-/**
- * Finds the appropriate configuration directory for a given host and path.
- *
- * @deprecated Use \Drupal\Core\Utility\Site::getMultisitePath() instead.
- */
-function find_conf_path($http_host, $script_name, $require_settings = TRUE, array $sites = array()) {
-  return $site->getMultisitePath($http_host, $script_name, $require_settings, $sites);
-}
-
-/**
  * Returns the path of a configuration directory.
  *
  * @param string $type
@@ -333,6 +303,8 @@ function config_get_config_directory($type = CONFIG_ACTIVE_DIRECTORY) {
  * @see \Symfony\Component\HttpFoundation\Request::getClientIP()
  */
 function drupal_override_server_variables($variables = array()) {
+  // @todo Neither \Drupal nor the class loader are available when this
+  //   function is called.
   $request = \Drupal::request();
   $server_vars = $request->server->all();
   // Allow the provided URL to override any existing values in $_SERVER.
@@ -361,8 +333,6 @@ function drupal_override_server_variables($variables = array()) {
   // Replace elements of the $_SERVER array, as appropriate.
   $request->server->replace($variables + $server_vars + $defaults);
 
-  // @todo remove once \Drupal\Core\Utility\Site::getMultisitePath() no longer
-  //   uses $_SERVER.
   $_SERVER = $request->server->all();
 }
 
@@ -451,27 +421,26 @@ function drupal_settings_initialize($require_settings = TRUE) {
   // Export these settings.php variables to the global namespace.
   global $sites, $databases, $cookie_domain, $conf, $db_prefix, $drupal_hash_salt, $base_secure_url, $base_insecure_url, $config_directories;
   $conf = array();
-  // Include the global settings.php to determine whether the multi-site
-  // functionality is enabled. If settings.php is not required, then the caller
-  // is likely the installer, in which case the global settings.php may be used
-  // to enable the multi-site functionality to install Drupal into a
-  // site-specific directory.
+
+  // Include settings.php to determine whether multi-site functionality is
+  // enabled. In the installer, $require_settings is FALSE, in which case the
+  // global settings.php may be used to enable the multi-site functionality
+  // to install Drupal into a site-specific directory.
   if ($require_settings || is_readable(DRUPAL_ROOT . '/settings.php')) {
     require_once DRUPAL_ROOT . '/settings.php';
   }
 
-  // Discover the site directory, priming the static cache in
-  // Site::determinePath(). Make $conf_path available as a local variable in
-  // settings.php.
-  if (isset($conf_path)) {
-    Site::setPath($conf_path);
-  }
+  // Discover the site directory.
+  require_once __DIR__ . '/../lib/Drupal/Core/Utility/Site.php';
+  Site::init(DRUPAL_ROOT, isset($sites) ? $sites : NULL, isset($conf_path) ? $conf_path : NULL, $require_settings);
+
+  // Make conf_path() available as local variable in settings.php.
   $conf_path = Site::getPath();
-  if (isset($sites) && Site::getPath() !== '.' && is_readable(Site::getAbsolutePath('settings.php'))) {
+  if (isset($sites) && Site::getPath() !== '' && is_readable(Site::getAbsolutePath('settings.php'))) {
     include_once Site::getAbsolutePath('settings.php');
   }
-  require_once __DIR__ . '../../lib/Drupal/Component/Utility/Settings.php';
 
+  require_once __DIR__ . '/../lib/Drupal/Component/Utility/Settings.php';
   new Settings(isset($settings) ? $settings : array());
 
   $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
@@ -1867,11 +1836,7 @@ function _drupal_bootstrap_configuration() {
   // Load the procedural configuration system helper functions.
   require_once __DIR__ . '/config.inc';
 
-  // Set the Drupal custom error handler.
-  // Circular dependency: The error/exception handler requires config, which
-  // requires the service container, which requires the class loader, which
-  // requires $conf/settings.php (to be swappable). Therefore, errors in early
-  // bootstrap and settings.php cannot be handled by Drupal.
+  // Set the Drupal custom error handler. (requires \Drupal::config())
   set_error_handler('_drupal_error_handler');
   set_exception_handler('_drupal_exception_handler');
 
@@ -2171,12 +2136,13 @@ function _drupal_load_test_overrides($test_prefix) {
   }
 
   // Check for and load a settings.php file in the simpletest files directory.
-  $filename = Site::getPath('/files/' . $path_prefix . '/settings.php');
+  $filename = Site::getAbsolutePath('files/' . $path_prefix . '/settings.php');
   if (file_exists($filename)) {
     $settings = settings()->getAll();
-    $conf_path = &drupal_static('conf_path');
+    $conf_path = Site::getPath();
     // This can override $conf, $conf_path, $settings, and $config_directories.
     include $filename;
+    Site::setPath($conf_path);
     // Keep the overriden $conf_path alive across drupal_static_reset() calls.
     // @see \Drupal\Core\Utility\Site::getSimpletestPath()
     $settings['simpletest_conf_path'] = $conf_path;
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 43085da..7e6cb05 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -285,11 +285,8 @@ function install_begin_request(&$install_state) {
   }
 
   // Perform a minimal bootstrap.
-  // This essentially calls _drupal_bootstrap_configuration(), which in turn
-  // calls drupal_settings_initialize() using the return value of
-  // drupal_installation_attempted() as argument. During installation, this
-  // causes drupal_settings_initialize() to not attempt to load any settings.php
-  // files, which allows to prime the site path to be used during installation.
+  // During installation, drupal_settings_initialize() will not attempt to load
+  // settings.php, so as to prime the site path to be used during installation.
   // By not requiring settings.php, a bare site folder can be prepared in the
   // /sites directory, which will be used for installing Drupal.
   drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);
@@ -1083,8 +1080,7 @@ function install_verify_database_settings() {
   global $databases;
   if (!empty($databases)) {
     $database = $databases['default']['default'];
-    $settings_file = Site::getPath('settings.php');
-    $errors = install_database_errors($database, $settings_file);
+    $errors = install_database_errors($database);
     if (empty($errors)) {
       return TRUE;
     }
@@ -1105,7 +1101,6 @@ function install_verify_database_settings() {
 function install_settings_form($form, &$form_state, &$install_state) {
   global $databases;
 
-  $settings_file = Site::getPath('settings.php');
   $database = isset($databases['default']['default']) ? $databases['default']['default'] : array();
 
   drupal_set_title(t('Database configuration'));
@@ -1152,7 +1147,6 @@ function install_settings_form($form, &$form_state, &$install_state) {
   );
 
   $form['errors'] = array();
-  $form['settings_file'] = array('#type' => 'value', '#value' => $settings_file);
 
   return $form;
 }
@@ -1186,7 +1180,7 @@ function install_settings_form_validate($form, &$form_state) {
   unset($database['db_prefix']);
 
   $form_state['storage']['database'] = $database;
-  $errors = install_database_errors($database, $form_state['values']['settings_file']);
+  $errors = install_database_errors($database);
   foreach ($errors as $name => $message) {
     form_set_error($name, $form_state, $message);
   }
@@ -1195,7 +1189,7 @@ function install_settings_form_validate($form, &$form_state) {
 /**
  * Checks a database connection and returns any errors.
  */
-function install_database_errors($database, $settings_file) {
+function install_database_errors($database) {
   global $databases;
   $errors = array();
 
@@ -1203,7 +1197,11 @@ function install_database_errors($database, $settings_file) {
   $database_types = drupal_get_database_types();
   $driver = $database['driver'];
   if (!isset($database_types[$driver])) {
-    $errors['driver'] = t("In your %settings_file file you have configured @drupal to use a %driver server, however your PHP installation currently does not support this database type.", array('%settings_file' => $settings_file, '@drupal' => drupal_install_profile_distribution_name(), '%driver' => $driver));
+    $errors['driver'] = t("In your %settings_file file you have configured @drupal to use a %driver server, however your PHP installation currently does not support this database type.", array(
+      '%settings_file' => Site::getPath('settings.php'),
+      '@drupal' => drupal_install_profile_distribution_name(),
+      '%driver' => $driver,
+    ));
   }
   else {
     // Run driver specific validation
@@ -2393,9 +2391,9 @@ function install_check_requirements($install_state) {
   if (!$install_state['settings_verified']) {
     $readable = FALSE;
     $writable = FALSE;
+    $conf_path = Site::getPath();
     $settings_file = Site::getPath('settings.php');
     $default_settings_file = './core/default.settings.php';
-    $conf_path = Site::getPath();
     $file = $conf_path;
     $exists = FALSE;
     // Verify that the directory exists.
diff --git a/core/lib/Drupal/Component/Utility/Path.php b/core/lib/Drupal/Component/Utility/Path.php
deleted file mode 100644
index 709d4a3..0000000
--- a/core/lib/Drupal/Component/Utility/Path.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Component\Utility\Path.
- */
-
-namespace Drupal\Component\Utility;
-
-/**
- * A utility class for path operations.
- */
-class Path {
-
-  /**
-   * Appends a suffix to a path.
-   *
-   * This function accounts for the possibility of $path being an empty string.
-   * Using the simple concatenation $path . '/' . $suffix would make the
-   * resulting string an absolute path in that case.
-   *
-   * @param string $path
-   *   The string to append the suffix to. May be an empty string.
-   * @param string $suffix
-   *   (optional) The string to append to the path.
-   *
-   * @return string
-   *   The concatenated string. If both $path and $suffix are empty strings, '.'
-   *   is returned. In case the return value is concatenated further with other
-   *   strings, this prevents the result from unwantendly becoming an absolute
-   *   path.
-   *
-   * @throws \InvalidArgumentException
-   */
-  public static function suffix($path, $suffix = NULL) {
-    if (!is_string($path)) {
-      throw new \InvalidArgumentException('The path must be a string.');
-    }
-
-    if ($path == '' && (!isset($suffix) || $suffix === '')) {
-      return '.';
-    }
-    elseif ($path == '' && isset($suffix)) {
-      return $suffix;
-    }
-    elseif ($path != '' && (!isset($suffix) || $suffix === '')) {
-      return $path;
-    }
-    // In this case both $path and $suffix are non-empty; all other combinations
-    // have been checked above.
-    else {
-      return $path . DIRECTORY_SEPARATOR . $suffix;
-    }
-  }
-
-
-} 
\ No newline at end of file
diff --git a/core/lib/Drupal/Core/SystemListing.php b/core/lib/Drupal/Core/SystemListing.php
index 923ee29..6d895a2 100644
--- a/core/lib/Drupal/Core/SystemListing.php
+++ b/core/lib/Drupal/Core/SystemListing.php
@@ -100,9 +100,12 @@ function scan($mask, $directory, $key = 'name') {
     $searchdir[] = $directory;
     $searchdir[] = 'sites/all/' . $directory;
 
-    if (file_exists(Site::getPath($directory))) {
-      $searchdir[] = Site::getPath($directory);
+    if (Site::getPath() !== '') {
+      if (file_exists(Site::getPath($directory))) {
+        $searchdir[] = Site::getPath($directory);
+      }
     }
+
     // @todo Find a way to skip ./config directories (but not modules/config).
     $nomask = '/^(CVS|lib|templates|css|js)$/';
     $files = array();
diff --git a/core/lib/Drupal/Core/Utility/Site.php b/core/lib/Drupal/Core/Utility/Site.php
index 4b81ad3..4e65216 100644
--- a/core/lib/Drupal/Core/Utility/Site.php
+++ b/core/lib/Drupal/Core/Utility/Site.php
@@ -7,11 +7,10 @@
 
 namespace Drupal\Core\Utility;
 
-use Drupal\Component\Utility\Path;
 use Drupal\Component\Utility\Settings;
 
 /**
- * A utility class for easy access to the site configuration path.
+ * A utility class for easy access to the site path.
  */
 class Site {
 
@@ -20,118 +19,141 @@ class Site {
    *
    * @var string
    */
-  protected static $root;
+  private $root;
 
   /**
-   * The relative path to the site directory.
-   *
-   * May be an empty string, in case the site configuration directory is the
-   * Drupal root directory.
-   *
-   * @var string
-   */
-  protected static $path;
-
-  /**
-   * Tracks whether or not a custom path was set.
+   * A multi-site mapping, as defined in settings.php.
    *
-   * @var bool
+   * @var array
    */
-  protected static $custom = FALSE;
+  private $sites;
 
   /**
-   * Returns the relative path to the site directory with an optional suffix.
-   *
-   * Returns the configuration path based on the site's hostname, port, and
-   * pathname. Uses Site::getMultisitePath() to find the current configuration
-   * directory, if applicable. See default.settings.php for examples on how the
-   * URL is converted to a directory.
-   *
-   * @param string $suffix
-   *   (optional) A suffix to append to the site path. Use this parameter
-   *   instead of appending strings to the site path manually, because the site
-   *   configuration directory may be equal to the Drupal root directory and
-   *   thus the site path is '.'.
-   *
-   * @return string
-   *   The relative path to the site configuration. If the site configuration
-   *   directory is the Drupal root directory and no suffix is supplied, '.'
-   *   will be returned.
+   * The relative path to the site directory.
    *
-   * @see default.settings.php
+   * May be an empty string, in case the site directory is the root directory.
    *
-   * @todo Since the logic in this method makes sense for arbitrary path
-   *   concatenations consider splitting this into a separate
+   * @var string
    */
-  public static function getPath($suffix = NULL) {
-    return Path::suffix(static::determinePath(), $suffix);
-  }
+  private $path;
+
+  private static $instance;
 
   /**
-   * Returns the absolute path to the site directory with an optional suffix.
-   *
-   * @param string $suffix
-   *   (optional) A suffix to append to the site path.
+   * Initializes the Site singleton.
    *
-   * @return string
-   *   The absolute path to the site configuration.
+   * @todo Consider to move the $require_settings=FALSE case into a dedicated
+   *   initInstaller() method.
    */
-  public static function getAbsolutePath($suffix = NULL) {
-    $root_path = Path::suffix(static::determineDrupalRoot(), static::determinePath());
-    return Path::suffix($root_path, $suffix);
+  public static function init($root_directory, array $sites = NULL, $custom_path = NULL, $require_settings = TRUE) {
+    if (isset(self::$instance)) {
+      throw new \BadMethodCallException('Site is initialized already.');
+    }
+    new self($root_directory, $sites, $custom_path, $require_settings);
+    return self::$instance;
   }
 
   /**
-   * Determines the Drupal root directory.
-   *
-   * This exists to avoid the dependence on the runtime DRUPAL_ROOT constant.
-   *
-   * @return string
-   *   The absolute path to the Drupal root directory.
+   * Constructs the Site singleton.
    */
-  protected static function determineDrupalRoot() {
-    if (!isset(static::$root)) {
-      static::$root = dirname(dirname(dirname(dirname(dirname(__DIR__)))));
+  private function __construct($root_directory, array $sites = NULL, $custom_path = NULL, $require_settings = TRUE) {
+    $this->root = $root_directory;
+    $this->sites = $sites;
+
+    // An explicitly defined $conf_path in /settings.php takes precedence.
+    if (isset($custom_path)) {
+      $this->path = $custom_path;
+    }
+    // Check for a Simpletest override.
+    elseif ($simpletest_path = $this->getSimpletestPath()) {
+      $this->path = $simpletest_path;
     }
-    static::$root;
+    // If the multi-site functionality was enabled in /settings.php, discover
+    // the path for the current site.
+    // $sites just needs to be defined; an explicit mapping is not required.
+    elseif (isset($sites)) {
+      $this->path = $this->determinePath($sites, $require_settings);
+    }
+    // If the multi-site functionality is not enabled, the Drupal root
+    // directory is the site directory.
+    else {
+      $this->path = '';
+    }
+    self::$instance = $this;
   }
 
   /**
-   * Determines the path to the site configuration.
+   * Finds the appropriate configuration directory for a given host and path.
+   *
+   * Finds a matching configuration directory file by stripping the website's
+   * hostname from left to right and pathname from right to left. By default,
+   * the directory must contain a 'settings.php' file for it to match. If the
+   * parameter $require_settings is set to FALSE, then a directory without a
+   * 'settings.php' file will match as well. The first configuration
+   * file found will be used and the remaining ones will be ignored. If no
+   * configuration file is found, returns a default value '$confdir/default'. See
+   * default.settings.php for examples on how the URL is converted to a directory.
+   *
+   * The settings.php file can define aliases in an associative array named
+   * $sites. The array is written in the format
+   * '<port>.<domain>.<path>' => 'directory'
+   *
+   * As an example, to create a directory alias for
+   * http://www.drupal.org:8080/mysite/test whose configuration file is in
+   * sites/example.com, the array should be defined as:
+   * @code
+   * $sites = array(
+   *   '8080.www.drupal.org.mysite.test' => 'example.com',
+   * );
+   * @endcode
+   *
+   * @param array $sites
+   *   A multi-site mapping, as defined in settings.php.
+   * @param bool $require_settings
+   *   Only configuration directories with an existing settings.php file
+   *   will be recognized. Defaults to TRUE. During initial installation,
+   *   this is set to FALSE so that Drupal can detect a matching directory,
+   *   then create a new settings.php file in it.
    *
    * @return string
-   *   The relative path to the site path. May be an empty string, in case the
-   *   site configuration directory is the Drupal root directory.
+   *   The path of the matching configuration directory. May be an empty string,
+   *   in case the site configuration directory is the root directory.
+   *
+   * @todo Inject a Request object in instead of relying on globals?
    */
-  protected static function determinePath() {
-    // @todo Instead of setting a global change drupal_settings_initialize() to
-    //   call a setSites() method on this object.
-    global $sites;
+  private function determinePath(array $sites, $require_settings) {
+    // The hostname and optional port number, e.g. "www.example.com" or
+    // "www.example.com:8080".
+    $http_host = $_SERVER['HTTP_HOST'];
+    // The part of the URL following the hostname, including the leading slash.
+    $script_name = $_SERVER['SCRIPT_NAME'];
+    if (!$script_name) {
+      $script_name = $_SERVER['SCRIPT_FILENAME'];
+    }
 
-    if (!isset(static::$path)) {
-      // Check for a simpletest override.
-      if ($simpletest_path = static::getSimpletestPath()) {
-        static::$path = $simpletest_path;
-      }
-      elseif (!empty($sites)) {
-        // @todo Require a request object to be passed in instead of relying on
-        //   globals.
-        $http_host = $_SERVER['HTTP_HOST'];
-        // @todo Why does other code rely only on $_SERVER['SCRIPT_NAME'] and
-        //   assume that to be non-empty?
-        $script_name = $_SERVER['SCRIPT_NAME'];
-        if (!$script_name) {
-          $script_name = $_SERVER['SCRIPT_FILENAME'];
+    $uri = explode('/', $script_name);
+    $server = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));
+    for ($i = count($uri) - 1; $i > 0; $i--) {
+      for ($j = count($server); $j > 0; $j--) {
+        $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));
+        // Check for an alias in $sites.
+        if (isset($sites[$dir])) {
+          $dir = $sites[$dir];
+          if (!$require_settings) {
+            return $dir;
+          }
+        }
+        if ($require_settings) {
+          if (file_exists($this->root . '/sites/' . $dir . '/settings.php')) {
+            return "sites/$dir";
+          }
+        }
+        elseif (file_exists($this->root . '/sites/' . $dir)) {
+          return "sites/$dir";
         }
-        static::$path = static::getMultisitePath($http_host, $script_name, static::$custom, $sites);
-      }
-      // If the multi-site functionality is not enabled, the Drupal root
-      // directory is the site directory.
-      else {
-        static::$path = '';
       }
     }
-    return static::$path;
+    return '';
   }
 
   /**
@@ -154,16 +176,21 @@ protected static function determinePath() {
    * @see \Drupal\Core\Utility\Site::determinePath()
    * @see _drupal_load_test_overrides()
    */
-  protected static function getSimpletestPath() {
+  private function getSimpletestPath() {
     // Ensure that the settings object is available. Site::getPath() is called
     // once before the Settings class is included, and at that point it should
     // still load the primary $conf_path. See drupal_settings_initialize().
-    // @todo Remove this, when possible.
     if (!class_exists('Drupal\Component\Utility\Settings', FALSE)) {
       return FALSE;
     }
 
     // If no $simpletest_conf_path is set, use the normal $conf_path.
+
+    // @todo Critical race condition: This class discovers settings.php, and
+    //   settings.php declares the $settings for instantiating Settings.
+    //   The Settings singleton is not and cannot be instantiated at this point
+    //   in time.
+
     if (!($simpletest_conf_path = Settings::getSingleton()->get('simpletest_conf_path'))) {
       return FALSE;
     }
@@ -179,65 +206,51 @@ protected static function getSimpletestPath() {
     return $simpletest_conf_path;
   }
 
+  private function resolvePath($filepath) {
+    if ($filepath !== '' && $filepath[0] === '/') {
+      $filepath = substr($filepath, 1);
+    }
+    if ($this->path !== '') {
+      if ($filepath !== '') {
+        $filepath = $this->path . '/' . $filepath;
+      }
+      else {
+        $filepath = $this->path;
+      }
+    }
+    return $filepath;
+  }
+
   /**
-   * Finds the appropriate configuration directory for a given host and path.
+   * Returns the relative path to the site directory with an optional suffix.
    *
-   * Finds a matching configuration directory file by stripping the website's
-   * hostname from left to right and pathname from right to left. By default,
-   * the directory must contain a 'settings.php' file for it to match. If the
-   * parameter $require_settings is set to FALSE, then a directory without a
-   * 'settings.php' file will match as well. The first configuration
-   * file found will be used and the remaining ones will be ignored. If no
-   * configuration file is found, returns a default value '$confdir/default'. See
-   * default.settings.php for examples on how the URL is converted to a directory.
+   * Use this function instead of appending strings to the site path manually,
+   * because the site directory may be the root directory and thus the resulting
+   * path would be an absolute filesystem path.
    *
-   * If a file named sites.php is present in the $confdir, it will be loaded
-   * prior to scanning for directories. That file can define aliases in an
-   * associative array named $sites. The array is written in the format
-   * '<port>.<domain>.<path>' => 'directory'. As an example, to create a
-   * directory alias for http://www.drupal.org:8080/mysite/test whose configuration
-   * file is in sites/example.com, the array should be defined as:
-   * @code
-   * $sites = array(
-   *   '8080.www.drupal.org.mysite.test' => 'example.com',
-   * );
-   * @endcode
-   *
-   * @param $http_host
-   *   The hostname and optional port number, e.g. "www.example.com" or
-   *   "www.example.com:8080".
-   * @param $script_name
-   *   The part of the URL following the hostname, including the leading slash.
-   * @param $require_settings
-   *   Defaults to TRUE. If TRUE, then only match directories with a
-   *   'settings.php' file. Otherwise match any directory.
-   * @param array $sites
-   *   A multi-site mapping, as defined in settings.php.
+   * @param string $filepath
+   *   (optional) A relative filepath to append to the site path.
    *
    * @return string
-   *   The path of the matching configuration directory.
-   *
-   * @see default.settings.php
-   * @see \Drupal\Core\Utility\Site::determinePath()
+   *   The given $filepath, potentially prefixed with the site path.
    */
-  public static function getMultisitePath($http_host, $script_name, $require_settings, array $sites) {
-    $uri = explode('/', $script_name);
-    $server = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));
-    for ($i = count($uri) - 1; $i > 0; $i--) {
-      for ($j = count($server); $j > 0; $j--) {
-        $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));
-        // Check for an alias in $sites.
-        if (isset($sites[$dir]) && file_exists(DRUPAL_ROOT . '/sites/' . $sites[$dir])) {
-          $dir = $sites[$dir];
-        }
-        if (file_exists(DRUPAL_ROOT . '/sites/' . $dir . '/settings.php') || (!$require_settings && file_exists(DRUPAL_ROOT . '/sites/' . $dir))) {
-          return "sites/$dir";
-        }
-      }
-    }
-    return 'sites/default';
+  public static function getPath($filepath = '') {
+    return self::$instance->resolvePath($filepath);
   }
 
+  /**
+   * Returns the absolute path to the site directory with an optional suffix.
+   *
+   * @param string $filepath
+   *   (optional) A relative filepath to append to the site path.
+   *
+   * @return string
+   *   The given $filepath, potentially prefixed with the site path, as an
+   *   absolute filesystem path.
+   */
+  public static function getAbsolutePath($filepath = '') {
+    return self::$instance->root . '/' . self::$instance->resolvePath($filepath);
+  }
 
   /**
    * Sets the site path to a given path.
@@ -246,18 +259,16 @@ public static function getMultisitePath($http_host, $script_name, $require_setti
    *   The relative path to the site configuration directory that will be set.
    */
   public static function setPath($path) {
-    static::$custom = TRUE;
-    static::$path = $path;
+    self::$instance->path = $path;
   }
 
   /**
    * Resets the statically cached site path.
+   *
+   * @todo To be removed prior to commit.
    */
   public static function reset() {
-    static::$path = NULL;
-    static::$custom = FALSE;
-    // static::$root is not reset because it only depends on the location of
-    // this file on the file system which cannot change during a single request.
+    self::$instance = NULL;
   }
 
 }