diff --git a/core/lib/Drupal/Core/Cache/CacheBackendInterface.php b/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
index 796573ced34..753e6a3e27e 100644
--- a/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
+++ b/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
@@ -68,6 +68,12 @@ interface CacheBackendInterface {
   /**
    * Stores data in the persistent cache.
    *
+   * Core cache implementations set the created time on cache item with
+   * microtime(TRUE) rather than REQUEST_TIME_FLOAT, because the created time
+   * of cache items should match when they are created, not when the request
+   * started. Apart from being more accurate, this increases the chance an
+   * item will legitimately be considered valid.
+   *
    * @param string $cid
    *   The cache ID of the data to store.
    * @param mixed $data
diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackend.php b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
index 3f15f43358f..09e7e827ee3 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackend.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
@@ -180,7 +180,7 @@ class DatabaseBackend implements CacheBackendInterface {
     $checksum = $this->checksumTags($flat_tags);
     $fields = array(
       'serialized' => 0,
-      'created' => REQUEST_TIME,
+      'created' => round(microtime(TRUE), 3),
       'expire' => $expire,
       'tags' => implode(' ', $flat_tags),
       'checksum_invalidations' => $checksum['invalidations'],
@@ -575,8 +575,10 @@ class DatabaseBackend implements CacheBackendInterface {
           'default' => 0,
         ),
         'created' => array(
-          'description' => 'A Unix timestamp indicating when the cache entry was created.',
-          'type' => 'int',
+          'description' => 'A timestamp with millisecond precision indicating when the cache entry was created.',
+          'type' => 'numeric',
+          'precision' => 14,
+          'scale' => 3,
           'not null' => TRUE,
           'default' => 0,
         ),
diff --git a/core/lib/Drupal/Core/Cache/PhpBackend.php b/core/lib/Drupal/Core/Cache/PhpBackend.php
index 81f5876d0c8..6c7fdd238f7 100644
--- a/core/lib/Drupal/Core/Cache/PhpBackend.php
+++ b/core/lib/Drupal/Core/Cache/PhpBackend.php
@@ -121,7 +121,7 @@ class PhpBackend implements CacheBackendInterface {
     $item = (object) array(
       'cid' => $cid,
       'data' => $data,
-      'created' => REQUEST_TIME,
+      'created' => round(microtime(TRUE), 3),
       'expire' => $expire,
     );
     $item->tags = $this->flattenTags($tags);
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/GenericCacheBackendUnitTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Cache/GenericCacheBackendUnitTestBase.php
index 0a9108cbe10..5df23c985b6 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Cache/GenericCacheBackendUnitTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/GenericCacheBackendUnitTestBase.php
@@ -142,7 +142,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $this->assert(is_object($cached), "Backend returned an object for cache id test1.");
     $this->assertIdentical($with_backslash, $cached->data);
     $this->assertTrue($cached->valid, 'Item is marked as valid.');
-    $this->assertEqual($cached->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
 
     $this->assertIdentical(FALSE, $backend->get('test2'), "Backend does not contain data for cache id test2.");
@@ -151,7 +151,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $this->assert(is_object($cached), "Backend returned an object for cache id test2.");
     $this->assertIdentical(array('value' => 3), $cached->data);
     $this->assertTrue($cached->valid, 'Item is marked as valid.');
-    $this->assertEqual($cached->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($cached->expire, REQUEST_TIME + 3, 'Expire time is correct.');
 
     $backend->set('test3', 'foobar', REQUEST_TIME - 3);
@@ -159,7 +159,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $cached = $backend->get('test3', TRUE);
     $this->assert(is_object($cached), 'Backend returned an object for cache id test3.');
     $this->assertFalse($cached->valid, 'Item is marked as valid.');
-    $this->assertEqual($cached->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($cached->expire, REQUEST_TIME - 3, 'Expire time is correct.');
 
     $this->assertIdentical(FALSE, $backend->get('test4'), "Backend does not contain data for cache id test4.");
@@ -169,7 +169,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $this->assert(is_object($cached), "Backend returned an object for cache id test4.");
     $this->assertIdentical($with_eof, $cached->data);
     $this->assertTrue($cached->valid, 'Item is marked as valid.');
-    $this->assertEqual($cached->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
 
     $this->assertIdentical(FALSE, $backend->get('test5'), "Backend does not contain data for cache id test5.");
@@ -179,7 +179,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $this->assert(is_object($cached), "Backend returned an object for cache id test5.");
     $this->assertIdentical($with_eof_and_semicolon, $cached->data);
     $this->assertTrue($cached->valid, 'Item is marked as valid.');
-    $this->assertEqual($cached->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
 
     $with_variable = array('foo' => '$bar');
@@ -274,7 +274,7 @@ abstract class GenericCacheBackendUnitTestBase extends DrupalUnitTestBase {
     $this->assert(isset($ret['test7']), "Existing cache id test7 is set.");
     // Test return - ensure that objects has expected properties.
     $this->assertTrue($ret['test2']->valid, 'Item is marked as valid.');
-    $this->assertEqual($ret['test2']->created, REQUEST_TIME, 'Created time is correct.');
+    $this->assertTrue($ret['test2']->created >= REQUEST_TIME && $ret['test2']->created < microtime(TRUE), 'Created time is correct.');
     $this->assertEqual($ret['test2']->expire, Cache::PERMANENT, 'Expire time is correct.');
     // Test return - ensure it does not contain nonexistent cache ids.
     $this->assertFalse(isset($ret['test19']), "Nonexistent cache id test19 is not set.");