diff --git a/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php b/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
index 03bbb3c52d..6a08ec68ae 100644
--- a/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
+++ b/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
@@ -1,184 +1,201 @@
 <?php
 
 final class PhabricatorPHPConfigSetupCheck extends PhabricatorSetupCheck {
 
   public function getDefaultGroup() {
     return self::GROUP_PHP;
   }
 
   public function getExecutionOrder() {
     return 0;
   }
 
   protected function executeChecks() {
+    if (version_compare(phpversion(), 7, '>=')) {
+      $message = pht(
+        'This version of Phabricator does not support PHP 7. You '.
+        'are running PHP %s.',
+        phpversion());
+
+      $this->newIssue('php.version7')
+        ->setIsFatal(true)
+        ->setName(pht('PHP 7 Not Supported'))
+        ->setMessage($message)
+        ->addLink(
+          'https://phurl.io/u/php7',
+          pht('Phabricator PHP 7 Compatibility Information'));
+
+      return;
+    }
+
     $safe_mode = ini_get('safe_mode');
     if ($safe_mode) {
       $message = pht(
         "You have '%s' enabled in your PHP configuration, but Phabricator ".
         "will not run in safe mode. Safe mode has been deprecated in PHP 5.3 ".
         "and removed in PHP 5.4.\n\nDisable safe mode to continue.",
         'safe_mode');
 
       $this->newIssue('php.safe_mode')
         ->setIsFatal(true)
         ->setName(pht('Disable PHP %s', 'safe_mode'))
         ->setMessage($message)
         ->addPHPConfig('safe_mode');
       return;
     }
 
     // Check for `disable_functions` or `disable_classes`. Although it's
     // possible to disable a bunch of functions (say, `array_change_key_case()`)
     // and classes and still have Phabricator work fine, it's unreasonably
     // difficult for us to be sure we'll even survive setup if these options
     // are enabled. Phabricator needs access to the most dangerous functions,
     // so there is no reasonable configuration value here which actually
     // provides a benefit while guaranteeing Phabricator will run properly.
 
     $disable_options = array('disable_functions', 'disable_classes');
     foreach ($disable_options as $disable_option) {
       $disable_value = ini_get($disable_option);
       if ($disable_value) {
 
         // By default Debian installs the pcntl extension but disables all of
         // its functions using configuration. Whitelist disabling these
         // functions so that Debian PHP works out of the box (we do not need to
         // call these functions from the web UI). This is pretty ridiculous but
         // it's not the users' fault and they haven't done anything crazy to
         // get here, so don't make them pay for Debian's unusual choices.
         // See: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=605571
         $fatal = true;
         if ($disable_option == 'disable_functions') {
           $functions = preg_split('/[, ]+/', $disable_value);
           $functions = array_filter($functions);
           foreach ($functions as $k => $function) {
             if (preg_match('/^pcntl_/', $function)) {
               unset($functions[$k]);
             }
           }
           if (!$functions) {
             $fatal = false;
           }
         }
 
         if ($fatal) {
           $message = pht(
             "You have '%s' enabled in your PHP configuration.\n\n".
             "This option is not compatible with Phabricator. Remove ".
             "'%s' from your configuration to continue.",
             $disable_option,
             $disable_option);
 
           $this->newIssue('php.'.$disable_option)
             ->setIsFatal(true)
             ->setName(pht('Remove PHP %s', $disable_option))
             ->setMessage($message)
             ->addPHPConfig($disable_option);
         }
       }
     }
 
     $overload_option = 'mbstring.func_overload';
     $func_overload = ini_get($overload_option);
     if ($func_overload) {
       $message = pht(
         "You have '%s' enabled in your PHP configuration.\n\n".
         "This option is not compatible with Phabricator. Disable ".
         "'%s' in your PHP configuration to continue.",
         $overload_option,
         $overload_option);
 
       $this->newIssue('php'.$overload_option)
         ->setIsFatal(true)
         ->setName(pht('Disable PHP %s', $overload_option))
         ->setMessage($message)
         ->addPHPConfig($overload_option);
     }
 
     $open_basedir = ini_get('open_basedir');
     if ($open_basedir) {
 
       // 'open_basedir' restricts which files we're allowed to access with
       // file operations. This might be okay -- we don't need to write to
       // arbitrary places in the filesystem -- but we need to access certain
       // resources. This setting is unlikely to be providing any real measure
       // of security so warn even if things look OK.
 
       $failures = array();
 
       try {
         $open_libphutil = class_exists('Future');
       } catch (Exception $ex) {
         $failures[] = $ex->getMessage();
       }
 
       try {
         $open_arcanist = class_exists('ArcanistDiffParser');
       } catch (Exception $ex) {
         $failures[] = $ex->getMessage();
       }
 
       $open_urandom = false;
       try {
         Filesystem::readRandomBytes(1);
         $open_urandom = true;
       } catch (FilesystemException $ex) {
         $failures[] = $ex->getMessage();
       }
 
       try {
         $tmp = new TempFile();
         file_put_contents($tmp, '.');
         $open_tmp = @fopen((string)$tmp, 'r');
         if (!$open_tmp) {
           $failures[] = pht(
             "Unable to read temporary file '%s'.",
             (string)$tmp);
         }
       } catch (Exception $ex) {
         $message = $ex->getMessage();
         $dir = sys_get_temp_dir();
         $failures[] = pht(
           "Unable to open temp files from '%s': %s",
           $dir,
           $message);
       }
 
       $issue = $this->newIssue('php.open_basedir')
         ->setName(pht('Disable PHP %s', 'open_basedir'))
         ->addPHPConfig('open_basedir');
 
       if ($failures) {
         $message = pht(
           "Your server is configured with '%s', which prevents Phabricator ".
           "from opening files it requires access to.\n\n".
           "Disable this setting to continue.\n\nFailures:\n\n%s",
           'open_basedir',
           implode("\n\n", $failures));
 
         $issue
           ->setIsFatal(true)
           ->setMessage($message);
 
         return;
       } else {
         $summary = pht(
           "You have '%s' configured in your PHP settings, which ".
           "may cause some features to fail.",
           'open_basedir');
 
         $message = pht(
           "You have '%s' configured in your PHP settings. Although this ".
           "setting appears permissive enough that Phabricator will work ".
           "properly, you may still run into problems because of it.\n\n".
           "Consider disabling '%s'.",
           'open_basedir',
           'open_basedir');
 
         $issue
           ->setSummary($summary)
           ->setMessage($message);
       }
     }
   }
 }
diff --git a/src/docs/user/installation_guide.diviner b/src/docs/user/installation_guide.diviner
index 8feb8ae1d0..749ca9a63d 100644
--- a/src/docs/user/installation_guide.diviner
+++ b/src/docs/user/installation_guide.diviner
@@ -1,179 +1,180 @@
 @title Installation Guide
 @group intro
 
 This document contains basic install instructions to get Phabricator up and
 running.
 
 Overview
 ========
 
 Phabricator is a LAMP (Linux, Apache, MySQL, PHP) application. To install
 Phabricator, you will need:
 
   - a normal computer to install it on (shared hosts and unusual environments
     are not supported) running some flavor of Linux or a similar OS;
   - a domain name (like `phabricator.mycompany.com`);
   - basic sysadmin skills;
   - Apache, nginx, or another webserver;
   - PHP, MySQL, and Git.
 
 The remainder of this document details these requirements.
 
 Installation Requirements
 =========================
 
 You will need **a computer**. Options include:
 
   - **A Normal Computer**: This is strongly recommended. Many installs use a VM
     in EC2. Phabricator installs properly and works well on a normal computer.
   - **A Shared Host**: This may work, but is not recommended. Many shared
     hosting environments have restrictions which prevent some of Phabricator's
     features from working. Consider using a normal computer instead. We do not
     support shared hosts.
   - **A SAN Appliance, Network Router, Gaming Console, Raspberry Pi, etc.**:
     Although you may be able to install Phabricator on specialized hardware, it
     is unlikely to work well and will be difficult for us to support. Strongly
     consider using a normal computer instead. We do not support specialized
     hardware.
   - **A Toaster, Car, Firearm, Thermostat, etc.**: Yes, many modern devices now
     have embedded computing capability. We live in interesting times. However,
     you should not install Phabricator on these devices. Instead, install it on
     a normal computer. We do not support installing on noncomputing devices.
 
 To install the Phabricator server software, you will need an **operating
 system** on your normal computer which is **not Windows**. Note that the
 command line interface //does// work on Windows, and you can //use//
 Phabricator from any operating system with a web browser. However, the server
 software does not run on Windows. It does run on most other operating systems,
 so choose one of these instead:
 
   - **Linux**: Most installs use Linux.
   - **Mac OS X**: Mac OS X is an acceptable flavor of Linux.
   - **FreeBSD**: While FreeBSD is certainly not a flavor of Linux, it is a fine
     operating system possessed of many desirable qualities, and Phabricator will
     install and run properly on FreeBSD.
   - **Solaris, etc.**: Other systems which look like Linux and quack like Linux
     will generally work fine, although we may suffer a reduced ability to
     support and resolve issues on unusual operating systems.
 
 Beyond an operating system, you will need **a webserver**.
 
   - **Apache**: Many installs use Apache + `mod_php`.
   - **nginx**: Many installs use nginx + `php-fpm`.
   - **lighttpd**: `lighttpd` is less popular than Apache or nginx, but it
     works fine.
   - **Other**: Other webservers which can run PHP are also likely to work fine,
     although these installation instructions will not cover how to set them up.
   - **PHP Builtin Server**: You can use the builtin PHP webserver for
     development or testing, although it should not be used in production.
 
 You will also need:
 
   - **MySQL**: You need MySQL. We strongly recommend MySQL 5.5 or newer.
-  - **PHP**: You need PHP 5.2 or newer.
+  - **PHP**: You need PHP 5.2 or newer, but note that PHP 7 is
+    **not supported**.
 
 You'll probably also need a **domain name**. In particular, you should read this
 note:
 
 NOTE: Phabricator must be installed on an entire domain. You can not install it
 to a path on an existing domain, like `example.com/phabricator/`. Instead,
 install it to an entire domain or subdomain, like `phabricator.example.com`.
 
 Level Requirements
 ==================
 
 To install and administrate Phabricator, you'll need to be comfortable with
 common system administration skills. For example, you should be familiar with
 using the command line, installing software on your operating system of choice,
 working with the filesystem, managing processes, dealing with permissions,
 editing configuration files, and setting environment variables.
 
 If you aren't comfortable with these skills, you can still try to perform an
 install. The install documentation will attempt to guide you through what you
 need to know. However, if you aren't very familiar or comfortable with using
 this set of skills to troubleshoot and resolve problems, you may encounter
 issues which you have substantial difficulty working through.
 
 We assume users installing and administrating Phabricator are comfortable with
 common system administration skills and concepts. If you aren't, proceed at
 your own risk and expect that your skills may be tested.
 
 Installing Required Components
 ==============================
 
 If you are installing on Ubuntu or an RedHat derivative, there are install
 scripts available which should handle most of the things discussed in this
 document for you:
 
   - **RedHat Derivatives**:
     [[ https://secure.phabricator.com/diffusion/P/browse/master/scripts/install/install_rhel-derivs.sh
      | install_rhel-derivs.sh ]]
   - **Ubuntu**:
     [[ https://secure.phabricator.com/diffusion/P/browse/master/scripts/install/install_ubuntu.sh
      | install_ubuntu.sh ]]
 
 If those work for you, you can skip directly to the
 @{article:Configuration Guide}. These scripts are also available in the
 `scripts/install` directory in the project itself.
 
 Otherwise, here's a general description of what you need to install:
 
   - git (usually called "git" in package management systems)
   - Apache (usually "httpd" or "apache2") (or nginx)
   - MySQL Server (usually "mysqld" or "mysql-server")
   - PHP (usually "php")
   - Required PHP extensions: mbstring, iconv, mysql (or mysqli), curl, pcntl
     (these might be something like "php-mysql" or "php5-mysql")
   - Optional PHP extensions: gd, apc (special instructions for APC are available
     below if you have difficulty installing it), xhprof (instructions below,
     you only need this if you are developing Phabricator)
 
 If you already have LAMP setup, you've probably already got everything you need.
 It may also be helpful to refer to the install scripts above, even if they don't
 work for your system.
 
 Now that you have all that stuff installed, grab Phabricator and its
 dependencies:
 
   $ cd somewhere/ # pick some install directory
   somewhere/ $ git clone https://github.com/phacility/libphutil.git
   somewhere/ $ git clone https://github.com/phacility/arcanist.git
   somewhere/ $ git clone https://github.com/phacility/phabricator.git
 
 = Installing APC (Optional) =
 
 Like everything else written in PHP, Phabricator will run much faster with APC
 installed. You likely need to install "pcre-devel" first:
 
   sudo yum install pcre-devel
 
 Then you have two options. Either install via PECL (try this first):
 
   sudo yum install php-pear
   sudo pecl install apc
 
 **If that doesn't work**, grab the package from PECL directly and follow the
 build instructions there:
 
 http://pecl.php.net/package/APC
 
 Installing APC is optional but **strongly recommended**, especially on
 production hosts.
 
 Once APC is installed, test that it is available by running:
 
   php -i | grep apc
 
 If it doesn't show up, add:
 
   extension=apc.so
 
 ..to "/etc/php.d/apc.ini" or the "php.ini" file indicated by "php -i".
 
 = Next Steps =
 
 Continue by:
 
   - configuring Phabricator with the @{article:Configuration Guide}; or
   - learning how to keep Phabricator up to date with
     @{article:Upgrading Phabricator}.