diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 52f574212a..20cd768108 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -24,6 +24,11 @@
  */
 const DRUPAL_MINIMUM_PHP = '5.5.9';
 
+/**
+ * Maximum supported version of PHP for Drupal 8.4.x and lower.
+ */
+const DRUPAL_MAXIMUM_PHP = '7.1.999';
+
 /**
  * Minimum recommended value of PHP memory_limit.
  *
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index bb69bd33f5..f8d1b0deef 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -184,6 +184,12 @@ function system_requirements($phase) {
     return $requirements;
   }
 
+  if (version_compare($phpversion, DRUPAL_MAXIMUM_PHP) > 0) {
+    $requirements['php']['description'] = t('Drupal 8.4.x is not compatible with PHP 7.2 and higher. Please use PHP 7.1.x.');
+    $requirements['php']['severity'] = REQUIREMENT_ERROR;
+    return $requirements;
+  }
+
   // Suggest to update to at least 5.5.21 or 5.6.5 for disabling multiple
   // statements.
   if (($phase === 'install' || \Drupal::database()->driver() === 'mysql') && !SystemRequirements::phpVersionWithPdoDisallowMultipleStatements($phpversion)) {