diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 601e97b..5c190ad 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -689,16 +689,20 @@ function drupal_settings_initialize() {
 
   // Make conf_path() available as local variable in settings.php.
   $conf_path = conf_path();
-  if (file_exists(DRUPAL_ROOT . '/' . $conf_path . '/settings.php')) {
-    include_once DRUPAL_ROOT . '/' . $conf_path . '/settings.php';
-  }
 
-  // If running as a SimpleTest child site, load additional per-test settings.
+  // If running within a test, load settings.php for this test run instead.
   if ($test_prefix = drupal_valid_test_ua()) {
-    if (file_exists(DRUPAL_ROOT . '/' . conf_path() . '/files/simpletest/' . substr($test_prefix, 10) . '/settings/simpletest_settings.php')) {
-      include_once DRUPAL_ROOT . '/' . conf_path() . '/files/simpletest/' . substr($test_prefix, 10) . '/settings/simpletest_settings.php';
+    $settings_file = DRUPAL_ROOT . '/' . conf_path() . '/files/simpletest/' . substr($test_prefix, 10) . '/settings.php';
+    if (file_exists($settings_file)) {
+      include_once $settings_file;
+    }
+    else {
+      die();
     }
   }
+  elseif (file_exists(DRUPAL_ROOT . '/' . $conf_path . '/settings.php')) {
+    include_once DRUPAL_ROOT . '/' . $conf_path . '/settings.php';
+  }
 
   $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
 
@@ -2334,13 +2338,12 @@ function _drupal_bootstrap_page_cache() {
       date_default_timezone_set(drupal_get_user_timezone());
       // If the skipping of the bootstrap hooks is not enforced, call
       // hook_boot. Hooks cannot be invoked without database access.
-      if (!variable_get('page_cache_without_database') && variable_get('page_cache_invoke_hooks', TRUE)) {
+      $invoke_boot_hooks = (!variable_get('page_cache_without_database') && variable_get('page_cache_invoke_hooks', TRUE));
+      if ($invoke_boot_hooks) {
         bootstrap_invoke_all('boot');
       }
       drupal_serve_page_from_cache($cache);
-      // If the skipping of the bootstrap hooks is not enforced, call
-      // hook_exit. Hooks cannot be invoked without database access.
-      if (!variable_get('page_cache_without_database') && variable_get('page_cache_invoke_hooks', TRUE)) {
+      if ($invoke_boot_hooks) {
         bootstrap_invoke_all('exit');
       }
       // We are done.
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 6884d69..d0c154f 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -87,9 +87,9 @@ abstract class TestBase {
   protected $setup = FALSE;
 
   /**
-   * A directory for simpletest to write a settings file to.
+   * The base filesystem directory for this test.
    */
-  protected $additionalSettingsDirectory;
+  protected $testFileDirectory;
 
   /**
    * Constructor for Test.
@@ -639,10 +639,10 @@ abstract class TestBase {
 
     // Create test directory ahead of installation so fatal errors and debug
     // information can be logged during installation process.
-    // Use temporary files directory with the same prefix as the database.
-    $this->public_files_directory = $this->originalFileDirectory . '/simpletest/' . substr($this->databasePrefix, 10);
-    $this->private_files_directory = $this->public_files_directory . '/private';
-    $this->temp_files_directory = $this->private_files_directory . '/temp';
+    $this->testFileDirectory = $this->originalFileDirectory . '/simpletest/' . substr($this->databasePrefix, 10);
+    $this->public_files_directory = $this->testFileDirectory . '/public';
+    $this->private_files_directory = $this->testFileDirectory . '/private';
+    $this->temp_files_directory = $this->testFileDirectory . '/temp';
 
     // Create the directories
     file_prepare_directory($this->public_files_directory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);
@@ -654,17 +654,11 @@ abstract class TestBase {
     // The child site automatically adjusts the global $config_directory_name to
     // a test-prefix-specific directory within the public files directory.
     // @see config_get_config_directory()
+    // Hint: $this->configFileDirectory == $this->testFileDirectory . '/config'
     $GLOBALS['config_directory_name'] = 'simpletest/' . substr($this->databasePrefix, 10) . '/config';
     $this->configFileDirectory = $this->originalFileDirectory . '/' . $GLOBALS['config_directory_name'];
     file_prepare_directory($this->configFileDirectory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);
 
-    // Create and set a new directory to store a simpletest_settings.php file.
-    // The child site loads this in addition to the primary settings.php file.
-    // @see drupal_settings_initialize()
-    $this->additionalSettingsDirectory = $this->originalFileDirectory . '/simpletest/' . substr($this->databasePrefix, 10) . '/settings';
-    file_prepare_directory($this->additionalSettingsDirectory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);
-    file_save_htaccess($this->additionalSettingsDirectory);
-
     // Log fatal errors.
     ini_set('log_errors', 1);
     ini_set('error_log', $this->public_files_directory . '/error.log');
@@ -699,7 +693,7 @@ abstract class TestBase {
     }
 
     // Delete temporary files directory.
-    file_unmanaged_delete_recursive($this->originalFileDirectory . '/simpletest/' . substr($this->databasePrefix, 10));
+    file_unmanaged_delete_recursive($this->testFileDirectory);
 
     // Restore original database connection.
     Database::removeConnection('default');
@@ -864,32 +858,4 @@ abstract class TestBase {
     }
     return $all_permutations;
   }
-
-  /**
-   * Creates simpletest_settings.php file.
-   *
-   * @param array $conf
-   *   Conf overrides to add to the simpletest_settings.php, for example:
-   *   @code
-   *     array(
-   *       'page_cache_without_database' = TRUE,
-   *     );
-   *   @endcode
-   */
-  protected function createSimpletestSettingsFile($conf = array()) {
-    include_once './core/includes/utility.inc';
-
-    $contents = <<<EOF
-<?php
-/**
- * @file
- * Simpletest specific configuration file.
- *
- */
-
-EOF;
-
-    $contents .= "\$conf = " . drupal_var_export($conf) . " + \$conf;\n";
-    file_put_contents($this->additionalSettingsDirectory . '/simpletest_settings.php', $contents);
-  }
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index f1a5f95..b2db751 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -587,6 +587,10 @@ abstract class WebTestBase extends TestBase {
     // Prepare the environment for running tests.
     $this->prepareEnvironment();
 
+    // Create settings.php file for this test.
+    // @see drupal_settings_initialize()
+    $this->createSettings();
+
     // Reset all statics and variables to perform tests in a clean environment.
     $conf = array();
     drupal_static_reset();
@@ -679,6 +683,48 @@ abstract class WebTestBase extends TestBase {
   }
 
   /**
+   * Creates a settings.php file for the site under test.
+   *
+   * @param array $conf
+   *   Conf overrides to add to settings.php; e.g.:
+   *   @code
+   *     array(
+   *       'page_cache_without_database' = TRUE,
+   *     );
+   *   @endcode
+   *
+   * @see drupal_settings_initialize()
+   */
+  protected function createSettings(array $new_conf = array()) {
+    include_once DRUPAL_ROOT . '/core/includes/utility.inc';
+
+    $settings_file = $this->testFileDirectory . '/settings.php';
+    // If the test site specific settings.php exists already, read/append to it.
+    if (file_exists($settings_file)) {
+      include $settings_file;
+    }
+    // Otherwise, use the parent site's settings.php as base.
+    else {
+      include DRUPAL_ROOT . '/' . conf_path() . '/settings.php';
+    }
+
+    $conf = array_merge($conf, $new_conf);
+    $contents = '<?php
+$databases = ' . drupal_var_export($databases) . ';
+$conf = ' . drupal_var_export($conf) . ';
+';
+    file_put_contents($settings_file, $contents);
+  }
+
+  /**
+   * Deletes the settings.php file for the site under test.
+   */
+  protected function deleteSettings() {
+    $settings_file = $this->testFileDirectory . '/settings.php';
+    unlink($settings_file);
+  }
+
+  /**
    * Preload the registry from the testing site.
    *
    * This method is called by Drupal\simpletest\WebTestBase::setUp(), and preloads
diff --git a/core/modules/system/lib/Drupal/system/Tests/Bootstrap/PageCacheTest.php b/core/modules/system/lib/Drupal/system/Tests/Bootstrap/PageCacheTest.php
index 9514946..851b924 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Bootstrap/PageCacheTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Bootstrap/PageCacheTest.php
@@ -125,8 +125,8 @@ class PageCacheTest extends WebTestBase {
         'page' => 'Drupal\bootstrap_test\Cache\TestBackend',
       ),
     );
+    $this->createSettings($conf);
 
-    $this->createSimpletestSettingsFile($conf);
     $this->drupalGet('');
     $this->assertText('Page returned by Drupal\bootstrap_test\Cache\TestBackend');
   }
diff --git a/core/modules/system/tests/modules/bootstrap_test/lib/Drupal/bootstrap_test/Cache/TestBackend.php b/core/modules/system/tests/modules/bootstrap_test/lib/Drupal/bootstrap_test/Cache/TestBackend.php
index 8812398..6b10ddb 100644
--- a/core/modules/system/tests/modules/bootstrap_test/lib/Drupal/bootstrap_test/Cache/TestBackend.php
+++ b/core/modules/system/tests/modules/bootstrap_test/lib/Drupal/bootstrap_test/Cache/TestBackend.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\bootstrap_test\Cache;
+
 use Drupal\Core\Cache\NullBackend;
 
 /**