diff --git a/commands/runserver/d8-rs-router.php b/commands/runserver/rs-router.php
similarity index 100%
rename from commands/runserver/d8-rs-router.php
rename to commands/runserver/rs-router.php
diff --git a/commands/runserver/runserver-prepend.php b/commands/runserver/rs-router_6.php
similarity index 96%
rename from commands/runserver/runserver-prepend.php
rename to commands/runserver/rs-router_6.php
index 5bf753292d..f00e5e77c0 100644
--- a/commands/runserver/runserver-prepend.php
+++ b/commands/runserver/rs-router_6.php
@@ -66,3 +66,6 @@ function runserver_env($key) {
     return getenv($key);
   }
 }
+
+// Note that we are simply prepended to the PHP request, we fall through to the
+// default PHP handling.
diff --git a/commands/runserver/rs-router_7.php b/commands/runserver/rs-router_7.php
new file mode 100644
index 0000000000..4475d7c83d
--- /dev/null
+++ b/commands/runserver/rs-router_7.php
@@ -0,0 +1,44 @@
+<?php
+
+// We hijack filter_init (which core filter module does not implement) as
+// a convenient place to affect early changes.
+if (!function_exists('filter_init')) {
+  // Check function_exists as a safety net in case it is added in future.
+  function filter_init() {
+    global $conf, $user;
+    // Inject values into the $conf array - will apply to all sites.
+    // This can be a useful place to apply generic development settings.
+    $conf_inject = unserialize(urldecode(runserver_env('RUNSERVER_CONF')));
+    // Merge in the injected conf, overriding existing items.
+    $conf = array_merge($conf, $conf_inject);
+  }
+}
+
+// We hijack system_watchdog (which core system module does not implement) as
+// a convenient place to capture logs.
+if (!function_exists('system_watchdog')) {
+  // Check function_exists as a safety net in case it is added in future.
+  function system_watchdog($log_entry = array()) {
+    // Drupal <= 7.x defines VERSION. Drupal 8 defines Drupal::VERSION instead.
+    if (defined('VERSION')) {
+      $uid = $log_entry['user']->uid;
+    }
+    else {
+      $uid = $log_entry['user']->id();
+    }
+    $message = strtr('Watchdog: !message | severity: !severity | type: !type | uid: !uid | !ip | !request_uri | !referer | !link', array(
+      '!message'     => strip_tags(!isset($log_entry['variables']) ? $log_entry['message'] : strtr($log_entry['message'], $log_entry['variables'])),
+      '!severity'    => $log_entry['severity'],
+      '!type'        => $log_entry['type'],
+      '!ip'          => $log_entry['ip'],
+      '!request_uri' => $log_entry['request_uri'],
+      '!referer'     => $log_entry['referer'],
+      '!uid'         => $uid,
+      '!link'        => strip_tags($log_entry['link']),
+    ));
+    error_log($message);
+  }
+}
+
+// Pass through to the default runserver router.
+include __DIR__ . '/rs-router.php';
diff --git a/commands/runserver/runserver.drush.inc b/commands/runserver/runserver.drush.inc
index b419486124..0edf7f4e76 100644
--- a/commands/runserver/runserver.drush.inc
+++ b/commands/runserver/runserver.drush.inc
@@ -131,11 +131,15 @@ function drush_core_runserver($uri = NULL) {
     drush_start_browser($browse, 2);
   }
   // Start the server using 'php -S'.
-  if (drush_drupal_major_version() >=8) {
-    $extra = ' "' . __DIR__ . '/d8-rs-router.php"';
+  if (drush_drupal_major_version() >= 8) {
+    $extra = ' "' . __DIR__ . '/rs-router.php"';
+  }
+  elseif (drush_drupal_major_version() == 7) {
+    $extra = ' "' . __DIR__ . '/rs-router_7.php"';
   }
   else {
-    $extra = ' --define auto_prepend_file="' . __DIR__ . '/runserver-prepend.php"';
+    // For Drupal 6 we prepend an include to what PHP was going invoke.
+    $extra = ' --define auto_prepend_file="' . __DIR__ . '/rs-router_6.php"';
   }
   $root = \Drush::bootstrapManager()->getRoot();
   drush_shell_exec_interactive('cd %s && %s -S ' . $addr . ':' . $uri['port']. $extra, $root, drush_get_option('php', 'php'));