diff --git a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
index af6d793033fc4..96ff653c3fa1a 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
@@ -65,15 +65,13 @@ function ($key, $value, $isHit) use ($defaultLifetime) {
         $this->mergeByLifetime = \Closure::bind(
             function ($deferred, $namespace, &$expiredIds) use ($getId) {
                 $byLifetime = array();
-                $now = time();
+                $now = microtime(true);
                 $expiredIds = array();
 
                 foreach ($deferred as $key => $item) {
                     if (null === $item->expiry) {
                         $ttl = 0 < $item->defaultLifetime ? $item->defaultLifetime : 0;
-                    } elseif ($item->expiry > $now) {
-                        $ttl = $item->expiry - $now;
-                    } else {
+                    } elseif (0 >= $ttl = (int) ($item->expiry - $now)) {
                         $expiredIds[] = $getId($key);
                         continue;
                     }
diff --git a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
index 17f2beaf0fe75..07fc198115a50 100644
--- a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
@@ -87,7 +87,7 @@ public function getItems(array $keys = array())
             CacheItem::validateKey($key);
         }
 
-        return $this->generateItems($keys, time(), $this->createCacheItem);
+        return $this->generateItems($keys, microtime(true), $this->createCacheItem);
     }
 
     /**
@@ -115,7 +115,7 @@ public function save(CacheItemInterface $item)
         $value = $item["\0*\0value"];
         $expiry = $item["\0*\0expiry"];
 
-        if (null !== $expiry && $expiry <= time()) {
+        if (null !== $expiry && $expiry <= microtime(true)) {
             $this->deleteItem($key);
 
             return true;
@@ -131,7 +131,7 @@ public function save(CacheItemInterface $item)
             }
         }
         if (null === $expiry && 0 < $item["\0*\0defaultLifetime"]) {
-            $expiry = time() + $item["\0*\0defaultLifetime"];
+            $expiry = microtime(true) + $item["\0*\0defaultLifetime"];
         }
 
         $this->values[$key] = $value;
diff --git a/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php b/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
index 1f471b663137b..13c1a7b05647f 100644
--- a/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
@@ -73,7 +73,7 @@ function (CacheItemInterface $innerItem, array $item) {
                     $item["\0*\0value"] = array("\x9D".pack('VN', $stats[CacheItem::STATS_EXPIRY] - CacheItem::STATS_EXPIRY_OFFSET, $stats[CacheItem::STATS_CTIME])."\x5F" => $item["\0*\0value"]);
                 }
                 $innerItem->set($item["\0*\0value"]);
-                $innerItem->expiresAt(null !== $item["\0*\0expiry"] ? \DateTime::createFromFormat('U', $item["\0*\0expiry"]) : null);
+                $innerItem->expiresAt(null !== $item["\0*\0expiry"] ? \DateTime::createFromFormat('U', (int) $item["\0*\0expiry"]) : null);
             },
             null,
             CacheItem::class
@@ -192,7 +192,7 @@ private function doSave(CacheItemInterface $item, $method)
         }
         $item = (array) $item;
         if (null === $item["\0*\0expiry"] && 0 < $item["\0*\0defaultLifetime"]) {
-            $item["\0*\0expiry"] = time() + $item["\0*\0defaultLifetime"];
+            $item["\0*\0expiry"] = microtime(true) + $item["\0*\0defaultLifetime"];
         }
         $innerItem = $item["\0*\0poolHash"] === $this->poolHash ? $item["\0*\0innerItem"] : $this->pool->getItem($this->namespace.$item["\0*\0key"]);
         ($this->setInnerItem)($innerItem, $item);
diff --git a/src/Symfony/Component/Cache/CHANGELOG.md b/src/Symfony/Component/Cache/CHANGELOG.md
index 1f5f539c8a07c..9cd4d00b4c2ca 100644
--- a/src/Symfony/Component/Cache/CHANGELOG.md
+++ b/src/Symfony/Component/Cache/CHANGELOG.md
@@ -4,6 +4,7 @@ CHANGELOG
 4.2.0
 -----
 
+ * added sub-second expiry accuracy for backends that support it
  * added `CacheInterface` and `TaggableCacheInterface`, providing stampede protection via probabilistic early expiration
  * throw `LogicException` when `CacheItem::tag()` is called on an item coming from a non tag-aware pool
  * deprecated `CacheItem::getPreviousTags()`, use `CacheItem::getStats()` instead
diff --git a/src/Symfony/Component/Cache/CacheItem.php b/src/Symfony/Component/Cache/CacheItem.php
index 8aa17df860ec2..9d8f28fe1769d 100644
--- a/src/Symfony/Component/Cache/CacheItem.php
+++ b/src/Symfony/Component/Cache/CacheItem.php
@@ -89,9 +89,9 @@ public function set($value)
     public function expiresAt($expiration)
     {
         if (null === $expiration) {
-            $this->expiry = $this->defaultLifetime > 0 ? time() + $this->defaultLifetime : null;
+            $this->expiry = $this->defaultLifetime > 0 ? microtime(true) + $this->defaultLifetime : null;
         } elseif ($expiration instanceof \DateTimeInterface) {
-            $this->expiry = (int) $expiration->format('U');
+            $this->expiry = (float) $expiration->format('U.u');
         } else {
             throw new InvalidArgumentException(sprintf('Expiration date must implement DateTimeInterface or be null, "%s" given', is_object($expiration) ? get_class($expiration) : gettype($expiration)));
         }
@@ -105,11 +105,11 @@ public function expiresAt($expiration)
     public function expiresAfter($time)
     {
         if (null === $time) {
-            $this->expiry = $this->defaultLifetime > 0 ? time() + $this->defaultLifetime : null;
+            $this->expiry = $this->defaultLifetime > 0 ? microtime(true) + $this->defaultLifetime : null;
         } elseif ($time instanceof \DateInterval) {
-            $this->expiry = (int) \DateTime::createFromFormat('U', time())->add($time)->format('U');
+            $this->expiry = microtime(true) + \DateTime::createFromFormat('U', 0)->add($time)->format('U.u');
         } elseif (\is_int($time)) {
-            $this->expiry = $time + time();
+            $this->expiry = $time + microtime(true);
         } else {
             throw new InvalidArgumentException(sprintf('Expiration date must be an integer, a DateInterval or null, "%s" given', is_object($time) ? get_class($time) : gettype($time)));
         }
diff --git a/src/Symfony/Component/Cache/Simple/ArrayCache.php b/src/Symfony/Component/Cache/Simple/ArrayCache.php
index d1ef583125b8b..6cef8b6e745c4 100644
--- a/src/Symfony/Component/Cache/Simple/ArrayCache.php
+++ b/src/Symfony/Component/Cache/Simple/ArrayCache.php
@@ -64,7 +64,7 @@ public function getMultiple($keys, $default = null)
             CacheItem::validateKey($key);
         }
 
-        return $this->generateItems($keys, time(), function ($k, $v, $hit) use ($default) { return $hit ? $v : $default; });
+        return $this->generateItems($keys, microtime(true), function ($k, $v, $hit) use ($default) { return $hit ? $v : $default; });
     }
 
     /**
@@ -121,7 +121,7 @@ public function setMultiple($values, $ttl = null)
                 }
             }
         }
-        $expiry = 0 < $ttl ? time() + $ttl : PHP_INT_MAX;
+        $expiry = 0 < $ttl ? microtime(true) + $ttl : PHP_INT_MAX;
 
         foreach ($valuesArray as $key => $value) {
             $this->values[$key] = $value;
diff --git a/src/Symfony/Component/Cache/Tests/Fixtures/ArrayCache.php b/src/Symfony/Component/Cache/Tests/Fixtures/ArrayCache.php
index 1a6157e822117..12081fa0411f4 100644
--- a/src/Symfony/Component/Cache/Tests/Fixtures/ArrayCache.php
+++ b/src/Symfony/Component/Cache/Tests/Fixtures/ArrayCache.php
@@ -21,12 +21,12 @@ protected function doContains($id)
 
         $expiry = $this->data[$id][1];
 
-        return !$expiry || time() <= $expiry || !$this->doDelete($id);
+        return !$expiry || microtime(true) <= $expiry || !$this->doDelete($id);
     }
 
     protected function doSave($id, $data, $lifeTime = 0)
     {
-        $this->data[$id] = array($data, $lifeTime ? time() + $lifeTime : false);
+        $this->data[$id] = array($data, $lifeTime ? microtime(true) + $lifeTime : false);
 
         return true;
     }
diff --git a/src/Symfony/Component/Cache/Traits/ArrayTrait.php b/src/Symfony/Component/Cache/Traits/ArrayTrait.php
index b7d2ad6d6299c..28a152bb53e02 100644
--- a/src/Symfony/Component/Cache/Traits/ArrayTrait.php
+++ b/src/Symfony/Component/Cache/Traits/ArrayTrait.php
@@ -44,7 +44,7 @@ public function hasItem($key)
     {
         CacheItem::validateKey($key);
 
-        return isset($this->expiries[$key]) && ($this->expiries[$key] >= time() || !$this->deleteItem($key));
+        return isset($this->expiries[$key]) && ($this->expiries[$key] >= microtime(true) || !$this->deleteItem($key));
     }
 
     /**
diff --git a/src/Symfony/Component/Cache/Traits/GetTrait.php b/src/Symfony/Component/Cache/Traits/GetTrait.php
index 71823c321e7c0..27f91fd4e08d5 100644
--- a/src/Symfony/Component/Cache/Traits/GetTrait.php
+++ b/src/Symfony/Component/Cache/Traits/GetTrait.php
@@ -69,7 +69,7 @@ private function doGet(CacheItemPoolInterface $pool, string $key, callable $call
             $save = \Closure::bind(
                 function (CacheItemPoolInterface $pool, CacheItemInterface $item, $value, float $startTime) {
                     if ($item instanceof CacheItem && $startTime && $item->expiry > $endTime = microtime(true)) {
-                        $item->newStats[CacheItem::STATS_EXPIRY] = $item->expiry;
+                        $item->newStats[CacheItem::STATS_EXPIRY] = (int) $item->expiry;
                         $item->newStats[CacheItem::STATS_CTIME] = 1000 * (int) ($endTime - $startTime);
                     }
                     $pool->save($item->set($value));