diff --git a/core/INSTALL.txt b/core/INSTALL.txt
index ac58ccbd6b4df250c0b2c8b8e0dfe6a00bc5379d..514e528fec7a822f3cac80fd52443c784b7de91e 100644
--- a/core/INSTALL.txt
+++ b/core/INSTALL.txt
@@ -18,7 +18,7 @@ Drupal requires:
 - A web server with PHP support, for example:
   - Apache 2.0 (or greater) (http://httpd.apache.org/).
   - Nginx 1.1 (or greater) (http://nginx.com/).
-- PHP 5.4.5 (or greater) (http://php.net/). For better security support it is
+- PHP 5.5.9 (or greater) (http://php.net/). For better security support it is
   recommended to update to at least 5.5.21 or 5.6.5.
 - One of the following databases:
   - MySQL 5.5.3 (or greater) (http://www.mysql.com/).
diff --git a/core/composer.json b/core/composer.json
index bbd6ef477d9a89b8e2e5e475902bda6c88060619..75814e2692474d449cb18169d23bcaa5caa6cf2e 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -4,7 +4,7 @@
   "type": "drupal-core",
   "license": "GPL-2.0+",
   "require": {
-    "php": ">=5.4.5",
+    "php": ">=5.5.9",
     "sdboyer/gliph": "0.1.*",
     "symfony/class-loader": "2.7.*",
     "symfony/console": "2.7.*",
diff --git a/core/composer.lock b/core/composer.lock
index 69c8f243865a3d8a447b8b0476e37541a5012f87..829db157b6e1a1ec3f585bcf1fb8e899e28312cd 100644
--- a/core/composer.lock
+++ b/core/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "90d27e9e043ff2ad0966a80a49ef2823",
+    "hash": "a842b991264d42a2f8c5cecbd82597b1",
     "packages": [
         {
             "name": "behat/mink",
@@ -3450,7 +3450,7 @@
     "prefer-stable": true,
     "prefer-lowest": false,
     "platform": {
-        "php": ">=5.4.5"
+        "php": ">=5.5.9"
     },
     "platform-dev": []
 }
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index d11e608219d24b5907e553794d094f240d9d00a3..7bfa55c3d286734f1592441826913e44758227f1 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -23,7 +23,7 @@
 /**
  * Minimum supported version of PHP.
  */
-const DRUPAL_MINIMUM_PHP = '5.4.5';
+const DRUPAL_MINIMUM_PHP = '5.5.9';
 
 /**
  * Minimum recommended value of PHP memory_limit.
diff --git a/core/install.php b/core/install.php
index d88444656eb55279f8130adef9c553a32980cee5..5940fbebe87d7a01e4fbcc54dc8c52b53e37fc2c 100644
--- a/core/install.php
+++ b/core/install.php
@@ -21,8 +21,8 @@
 // The minimum version is specified explicitly, as DRUPAL_MINIMUM_PHP is not
 // yet available. It is defined in bootstrap.inc, but it is not possible to
 // load that file yet as it would cause a fatal error on older versions of PHP.
-if (version_compare(PHP_VERSION, '5.4.5') < 0) {
-  print 'Your PHP installation is too old. Drupal requires at least PHP 5.4.5. See the <a href="https://www.drupal.org/requirements">system requirements</a> page for more information.';
+if (version_compare(PHP_VERSION, '5.5.9') < 0) {
+  print 'Your PHP installation is too old. Drupal requires at least PHP 5.5.9. See the <a href="https://www.drupal.org/requirements">system requirements</a> page for more information.';
   exit;
 }
 
diff --git a/core/lib/Drupal/Component/Plugin/composer.json b/core/lib/Drupal/Component/Plugin/composer.json
index e2d02402296b399dc763ab6cf35432453ee09311..826685d1145fd9f0ed1d1f5107dd7433903b5fda 100644
--- a/core/lib/Drupal/Component/Plugin/composer.json
+++ b/core/lib/Drupal/Component/Plugin/composer.json
@@ -5,7 +5,7 @@
     "homepage": "https://www.drupal.org/project/drupal",
     "license": "GPL-2.0+",
     "require": {
-        "php": ">=5.4.2"
+        "php": ">=5.5.9"
     },
     "autoload": {
         "psr-0": {
diff --git a/core/lib/Drupal/Component/ProxyBuilder/composer.json b/core/lib/Drupal/Component/ProxyBuilder/composer.json
index c941c6ede5abd6be380754fedbec4db4d4848202..126c1a339c71829cd1a98539d8045579652d4a50 100644
--- a/core/lib/Drupal/Component/ProxyBuilder/composer.json
+++ b/core/lib/Drupal/Component/ProxyBuilder/composer.json
@@ -5,7 +5,7 @@
   "homepage": "https://www.drupal.org/project/drupal",
   "license": "GPL-2.0+",
   "require": {
-    "php": ">=5.4.2",
+    "php": ">=5.5.9",
     "symfony/dependency-injection": "~2.6"
   },
   "autoload": {
diff --git a/core/lib/Drupal/Component/Utility/composer.json b/core/lib/Drupal/Component/Utility/composer.json
index af0c31b512822945e6eeeea417ecaa1382785c35..a029d1e45f776cbae8b478a3620bf9a54840551f 100644
--- a/core/lib/Drupal/Component/Utility/composer.json
+++ b/core/lib/Drupal/Component/Utility/composer.json
@@ -5,7 +5,7 @@
   "homepage": "https://www.drupal.org/project/drupal",
   "license": "GPL-2.0+",
   "require": {
-    "php": ">=5.3.10"
+    "php": ">=5.5.9"
   },
   "autoload": {
     "psr-0": {