diff -u /dev/null b/core/modules/system/src/Tests/Bootstrap/GetFilenameUnitTest.php
--- /dev/null
+++ b/core/modules/system/src/Tests/Bootstrap/GetFilenameUnitTest.php
@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\system\Tests\Bootstrap\GetFilenameUnitTest.
+ */
+
+namespace Drupal\system\Tests\Bootstrap;
+
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests that drupal_get_filename() works correctly.
+ *
+ * @group Bootstrap
+ */
+class GetFilenameUnitTest extends KernelTestBase {
+
+  /**
+   * The container used by the test, moved out of the way.
+   *
+   * @var \Symfony\Component\DependencyInjection\ContainerInterface
+   */
+  protected $previousContainer;
+
+  /**
+   * Tests that drupal_get_filename() works when the file is not in database.
+   */
+  function testDrupalGetFilename() {
+    // drupal_get_profile() is using obtaining the profile from state if the
+    // install_state global is not set.
+    global $install_state;
+    $install_state['parameters']['profile'] = 'testing';
+
+    // Rebuild system.module.files state cache.
+    drupal_static_reset('system_rebuild_module_data');
+    system_rebuild_module_data();
+
+    // Retrieving the location of a module.
+    $this->assertIdentical(drupal_get_filename('module', 'system'), 'core/modules/system/system.info.yml');
+
+    // Retrieving the location of a theme.
+    \Drupal::service('theme_handler')->install(array('stark'));
+    $this->assertIdentical(drupal_get_filename('theme', 'stark'), 'core/themes/stark/stark.info.yml');
+
+    // Retrieving the location of a theme engine.
+    $this->assertIdentical(drupal_get_filename('theme_engine', 'twig'), 'core/themes/engines/twig/twig.info.yml');
+
+    // Retrieving the location of a profile. Profiles are a special case with
+    // a fixed location and naming.
+    $this->assertIdentical(drupal_get_filename('profile', 'testing'), 'core/profiles/testing/testing.info.yml');
+
+
+    // Generate a non-existing module name.
+    $non_existing_module = uniqid("", TRUE);
+
+    // Set a custom error handler so we can ignore the file not found error.
+    set_error_handler(function($severity, $message, $file, $line) {
+      // Skip error handling if this is a "file not found" error.
+      if (strstr($message, 'is missing from the file system:')) {
+        \Drupal::state()->set('get_filename_test_triggered_error', TRUE);
+        return;
+      }
+      throw new \ErrorException($message, 0, $severity, $file, $line);
+    });
+    $this->assertNull(drupal_get_filename('module', $non_existing_module), 'Searching for an item that does not exist returns NULL.');
+    $this->assertTrue(\Drupal::state()->get('get_filename_test_triggered_error'), 'Searching for an item that does not exist triggers an error.');
+    // Restore the original error handler.
+    restore_error_handler();
+  }
+}
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
+++ b/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
@@ -125,8 +125,9 @@ public function __construct($root) {
    */
   public function scan($type, $include_tests = NULL) {
     // Determine the installation profile directories to scan for extensions,
-    // unless explicit profile directories have been set.
-    if (!isset($this->profileDirectories)) {
+    // unless explicit profile directories have been set. Exclude profiles
+    // as we can't have profiles within profiles.
+    if (!isset($this->profileDirectories) && $type != 'profile') {
       $this->setProfileDirectoriesFromSettings();
     }
 
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Extension/ThemeHandler.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandler.php
@@ -466,7 +466,8 @@ public function rebuildThemeData() {
     );
 
     $sub_themes = array();
-    $files = array();
+    $files_theme = array();
+    $files_theme_engine = array();
     // Read info files for each theme.
     foreach ($themes as $key => $theme) {
       // @todo Remove all code that relies on the $status property.
@@ -495,6 +496,7 @@ public function rebuildThemeData() {
       if (isset($engines[$engine])) {
         $theme->owner = $engines[$engine]->getExtensionPathname();
         $theme->prefix = $engines[$engine]->getName();
+        $files_theme_engine[$engine] = $engines[$engine]->getPathname();
       }
 
       // Prefix screenshot with theme path.
@@ -502,7 +504,7 @@ public function rebuildThemeData() {
         $theme->info['screenshot'] = $theme->getPath() . '/' . $theme->info['screenshot'];
       }
 
-      $files[$key] = $theme->getPathname();
+      $files_theme[$key] = $theme->getPathname();
     }
     // Build dependencies.
     // @todo Move into a generic ExtensionHandler base class.
@@ -511,7 +513,8 @@ public function rebuildThemeData() {
 
     // Store filenames to allow system_list() and drupal_get_filename() to
     // retrieve them without having to scan the filesystem.
-    $this->state->set('system.theme.files', $files);
+    $this->state->set('system.theme.files', $files_theme);
+    $this->state->set('system.theme_engine.files', $files_theme_engine);
 
     // After establishing the full list of available themes, fill in data for
     // sub-themes.
only in patch2:
unchanged:
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -883,14 +883,19 @@ function system_get_info($type, $name = NULL) {
  */
 function _system_rebuild_module_data() {
   $listing = new ExtensionDiscovery(\Drupal::root());
-  // Find modules
-  $modules = $listing->scan('module');
 
   // Find installation profiles.
   $profiles = $listing->scan('profile');
+  $profile = drupal_get_profile();
+  if ($profile && isset($profiles[$profile])) {
+    // Prime drupal_get_filename() with the profile info file location.
+    drupal_get_filename('profile', $profile, $profiles[$profile]->getPathname());
+  }
 
+  // Find modules
+  $modules = $listing->scan('module');
   // Include the installation profile in modules that are loaded.
-  if ($profile = drupal_get_profile()) {
+  if ($profile) {
     $modules[$profile] = $profiles[$profile];
     // Installation profile hooks are always executed last.
     $modules[$profile]->weight = 1000;