diff -u b/core/lib/Drupal/Core/Cache/MemoryBackend.php b/core/lib/Drupal/Core/Cache/MemoryBackend.php
--- b/core/lib/Drupal/Core/Cache/MemoryBackend.php
+++ b/core/lib/Drupal/Core/Cache/MemoryBackend.php
@@ -201,7 +201,7 @@
    * @return int
    */
   protected function getRequestTime() {
-    return \Drupal::time()->getRequestTime();
+    return \Drupal::hasContainer() ? \Drupal::time()->getRequestTime() : (int) $_SERVER['REQUEST_TIME'];
   }
 
   /**
reverted:
--- b/core/lib/Drupal/Core/Logger/LoggerChannel.php
+++ a/core/lib/Drupal/Core/Logger/LoggerChannel.php
@@ -105,7 +105,7 @@
       'request_uri' => '',
       'referer' => '',
       'ip' => '',
+      'timestamp' => time(),
-      'timestamp' => \Drupal::time()->getCurrentTime(),
     ];
     // Some context values are only available when in a request context.
     if ($this->requestStack && $request = $this->requestStack->getCurrentRequest()) {
diff -u b/core/lib/Drupal/Core/Path/AliasManager.php b/core/lib/Drupal/Core/Path/AliasManager.php
--- b/core/lib/Drupal/Core/Path/AliasManager.php
+++ b/core/lib/Drupal/Core/Path/AliasManager.php
@@ -294,7 +294,7 @@
    * @return int
    */
   protected function getRequestTime() {
-    return \Drupal::time()->getRequestTime();
+    return \Drupal::hasContainer() ? \Drupal::time()->getRequestTime() : $_SERVER['REQUEST_TIME'];
   }
 
 }
reverted:
--- b/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php
+++ a/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php
@@ -275,7 +275,7 @@
       ->willReturn($has_field);
 
     if (empty($this->timestamp)) {
+      $this->timestamp = time();
-      $this->timestamp = \Drupal::time()->getCurrentTime();
     }
     $field_item = (object) [
       'status' => $comment_status,
reverted:
--- b/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php
+++ a/core/tests/Drupal/Tests/Component/Datetime/TimeTest.php
@@ -104,7 +104,7 @@
 namespace Drupal\Component\Datetime;
 
 /**
+ * Shadow time() system call.
- * Shadow \Drupal::time()->getCurrentTime() system call.
  *
  * @returns int
  */
reverted:
--- b/core/tests/Drupal/Tests/Core/Asset/AssetResolverTest.php
+++ a/core/tests/Drupal/Tests/Core/Asset/AssetResolverTest.php
@@ -142,7 +142,7 @@
   }
 
   public function providerAttachedAssets() {
+    $time = time();
-    $time = \Drupal::time()->getCurrentTime();
     return [
       'same libraries, different timestamps' => [
         (new AttachedAssets())->setAlreadyLoadedLibraries([])->setLibraries(['core/drupal'])->setSettings(['currentTime' => $time]),
reverted:
--- b/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php
+++ a/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php
@@ -196,7 +196,7 @@
   public function testDeleteAllPropagation() {
     // Set both expiring and permanent keys.
     $this->chain->set('test1', 1, Cache::PERMANENT);
+    $this->chain->set('test2', 3, time() + 1000);
-    $this->chain->set('test2', 3, \Drupal::time()->getCurrentTime() + 1000);
     $this->chain->deleteAll();
 
     $this->assertFalse($this->firstBackend->get('test1'), 'First key has been deleted in first backend.');
reverted:
--- b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
+++ a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
@@ -65,13 +65,13 @@
     $timestamp_item = (object) [
       'cid' => ChainedFastBackend::LAST_WRITE_TIMESTAMP_PREFIX . 'cache_foo',
       // Time travel is easy.
+      'data' => time() + 60,
-      'data' => \Drupal::time()->getCurrentTime() + 60,
     ];
     $cache_item = (object) [
       'cid' => 'foo',
       'data' => 'baz',
+      'created' => time(),
+      'expire' => time() + 3600,
-      'created' => \Drupal::time()->getCurrentTime(),
-      'expire' => \Drupal::time()->getCurrentTime() + 3600,
       'tags' => ['tag'],
     ];
 
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Tests\Core\Render;
 
+use Drupal\Component\Datetime\Time;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Cache\Context\ContextCacheKeys;
@@ -110,6 +111,13 @@
     ],
   ];
 
+  /**
+   * System time service.
+   *
+   * @var \Drupal\Component\Datetime\TimeInterface
+   */
+  protected $datetimeTime;
+
   /**
    * {@inheritdoc}
    */
@@ -169,11 +177,13 @@ protected function setUp() {
     $this->placeholderGenerator = new PlaceholderGenerator($this->rendererConfig);
     $this->renderCache = new PlaceholderingRenderCache($this->requestStack, $this->cacheFactory, $this->cacheContextsManager, $this->placeholderGenerator);
     $this->renderer = new Renderer($this->controllerResolver, $this->themeManager, $this->elementInfo, $this->placeholderGenerator, $this->renderCache, $this->requestStack, $this->rendererConfig);
+    $this->datetimeTime = new Time($this->requestStack);
 
     $container = new ContainerBuilder();
     $container->set('cache_contexts_manager', $this->cacheContextsManager);
     $container->set('render_cache', $this->renderCache);
     $container->set('renderer', $this->renderer);
+    $container->set('datetime.time', $this->datetimeTime);
     \Drupal::setContainer($container);
   }