diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index fc36f66..5c5f633 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -1093,29 +1093,17 @@ protected function initializeRequestGlobals(Request $request) {
     // Set and derived from $base_url by this function.
     global $base_path, $base_root;
     global $base_secure_url, $base_insecure_url;
-
     // Create base URL.
+    $base_path = $request->getBasePath();
+    // Requests to 'core/foo.php' bypass the front controller, causing
+    // $request->getBasePath() to return a string ending with '/core'. In these
+    // cases, remove '/core' to obtain the correct $base_path.
+    if (substr($base_path, -5) == '/core') {
+      $base_path = substr($base_path, 0, strlen($base_path) - 5);
+    }
+    $base_path .= '/';
     $base_root = $request->getSchemeAndHttpHost();
-    $base_url = $base_root;
-
-    // For a request URI of '/index.php/foo', $_SERVER['SCRIPT_NAME'] is
-    // '/index.php', whereas $_SERVER['PHP_SELF'] is '/index.php/foo'.
-    if ($dir = rtrim(dirname($request->server->get('SCRIPT_NAME')), '\/')) {
-      // Remove "core" directory if present, allowing install.php,
-      // authorize.php, and others to auto-detect a base path.
-      $core_position = strrpos($dir, '/core');
-      if ($core_position !== FALSE && strlen($dir) - 5 == $core_position) {
-        $base_path = substr($dir, 0, $core_position);
-      }
-      else {
-        $base_path = $dir;
-      }
-      $base_url .= $base_path;
-      $base_path .= '/';
-    }
-    else {
-      $base_path = '/';
-    }
+    $base_url = rtrim($base_root . $base_path, '\/');
     $base_secure_url = str_replace('http://', 'https://', $base_url);
     $base_insecure_url = str_replace('https://', 'http://', $base_url);
   }
diff --git a/core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelTest.php b/core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelTest.php
index 7278fd6..767af77 100644
--- a/core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelTest.php
+++ b/core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelTest.php
@@ -13,6 +13,8 @@
    * @group DrupalKernel
    */
   class DrupalKernelTest extends UnitTestCase {
+    //Back up and restore any global variables that may be changed by tests.
+    protected $backupGlobals = FALSE;
 
     /**
      * Tests hostname validation with settings.
@@ -192,6 +194,38 @@ public function testFindSitePath() {
       $this->assertEquals('sites/example', DrupalKernel::findSitePath($request, FALSE, $vfs_root->url('drupal_root')));
     }
 
+    /**
+     * @covers ::initializeRequestGlobals
+     * @dataProvider initializeSettingsProvider
+     */
+    public function testInitializeSettings($path, $url, $expected_base_url, $expected_base_path, $expected_base_root) {
+      global $base_url;
+      global $base_path, $base_root;
+
+      $request = $this->prophesize(Request::class);
+      $request->getBasePath()->willReturn($path);
+      $request->getSchemeAndHttpHost()->willReturn($url);
+      $drupalKernel = new DrupalKernel('test', NULL);
+      $method = new \ReflectionMethod('Drupal\Core\DrupalKernel', 'initializeRequestGlobals');
+      $method->setAccessible(TRUE);
+      $method->invoke($drupalKernel, $request->reveal());
+      $this->assertSame($expected_base_path, $base_path);
+      $this->assertSame($expected_base_url, $base_url);
+      $this->assertSame($expected_base_root, $base_root);
+    }
+
+    /**
+     * Provides data for testInitializeSettings().
+     */
+    public function initializeSettingsProvider() {
+      return [
+        ['', 'http://localhost', 'http://localhost', '/', 'http://localhost'],
+        ['/drupal', 'http://localhost', 'http://localhost/drupal', '/drupal/', 'http://localhost'],
+        ['/core', 'http://localhost', 'http://localhost', '/', 'http://localhost'],
+        ['/drupal/core', 'http://localhost', 'http://localhost/drupal', '/drupal/', 'http://localhost'],
+      ];
+    }
+
   }
 
   /**