diff --git a/NEWS b/NEWS
index 01bc51d2a757f..c59c9a967c40e 100644
--- a/NEWS
+++ b/NEWS
@@ -25,6 +25,10 @@ PHP                                                                        NEWS
     its name to be reused. (David Carlier)
   . Added Iterable support for pgsql_copy_from. (David Carlier)
 
+- POSIX:
+  . Added POSIX_SC_OPEN_MAX constant to get the number of file descriptors
+    a process can handle. (David Carlier)
+
 - Random:
   . Moves from /dev/urandom usage to arc4random_buf on Haiku. (David Carlier)
 
diff --git a/UPGRADING b/UPGRADING
index 0f7b61d71b965..a336173ffd8b0 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -117,6 +117,9 @@ PHP 8.5 UPGRADE NOTES
 10. New Global Constants
 ========================================
 
+- POSIX:
+  . POSIX_SC_OPEN_MAX.
+
 ========================================
 11. Changes to INI File Handling
 ========================================
diff --git a/ext/posix/posix.stub.php b/ext/posix/posix.stub.php
index d34415107a07f..2ee9cdbc31473 100644
--- a/ext/posix/posix.stub.php
+++ b/ext/posix/posix.stub.php
@@ -303,6 +303,13 @@
  */
 const POSIX_PC_SYMLINK_MAX = UNKNOWN;
 #endif
+#ifdef _SC_OPEN_MAX
+/**
+ * @var int
+ * @cvalue _SC_OPEN_MAX
+ */
+const POSIX_SC_OPEN_MAX = UNKNOWN;
+#endif
 
 function posix_kill(int $process_id, int $signal): bool {}
 
diff --git a/ext/posix/posix_arginfo.h b/ext/posix/posix_arginfo.h
index 664d822db9eda..dceac3eabc995 100644
--- a/ext/posix/posix_arginfo.h
+++ b/ext/posix/posix_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 82caf527a8ec686bc450e5d782bb79275d5a13e3 */
+ * Stub hash: 25e0aa769d72988ebca07fff96c8ed1fcb6b7d5e */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_posix_kill, 0, 2, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, process_id, IS_LONG, 0)
@@ -461,4 +461,7 @@ static void register_posix_symbols(int module_number)
 #if defined(_PC_SYMLINK_MAX)
 	REGISTER_LONG_CONSTANT("POSIX_PC_SYMLINK_MAX", _PC_SYMLINK_MAX, CONST_PERSISTENT);
 #endif
+#if defined(_SC_OPEN_MAX)
+	REGISTER_LONG_CONSTANT("POSIX_SC_OPEN_MAX", _SC_OPEN_MAX, CONST_PERSISTENT);
+#endif
 }
diff --git a/ext/posix/tests/posix_sysconf.phpt b/ext/posix/tests/posix_sysconf.phpt
index 6acebe1f0e0f3..026aecacc4ef8 100644
--- a/ext/posix/tests/posix_sysconf.phpt
+++ b/ext/posix/tests/posix_sysconf.phpt
@@ -7,8 +7,10 @@ posix
 var_dump(posix_sysconf(-1));
 var_dump(posix_errno() != 0);
 var_dump(posix_sysconf(POSIX_SC_NPROCESSORS_ONLN));
+var_dump(posix_sysconf(POSIX_SC_OPEN_MAX) >= 256);
 ?>
 --EXPECTF--
 int(-1)
 bool(false)
 int(%d)
+bool(true)