diff --git a/include/zephyr/posix/posix_features.h b/include/zephyr/posix/posix_features.h
index e4a91c6fc92cec..94789c5acb23a8 100644
--- a/include/zephyr/posix/posix_features.h
+++ b/include/zephyr/posix/posix_features.h
@@ -223,7 +223,13 @@
 #define _XOPEN_VERSION 700
 /* #define _XOPEN_CRYPT (-1L) */
 /* #define _XOPEN_ENH_I18N (-1L) */
-/* #define _XOPEN_REALTIME (-1L) */
+#if defined(CONFIG_XSI_REALTIME) ||                                                                \
+	(defined(CONFIG_POSIX_FSYNC) && defined(CONFIG_POSIX_MEMLOCK) &&                           \
+	 defined(CONFIG_POSIX_MEMLOCK_RANGE) && defined(CONFIG_POSIX_MESSAGE_PASSING) &&           \
+	 defined(CONFIG_POSIX_PRIORITY_SCHEDULING) &&                                              \
+	 defined(CONFIG_POSIX_SHARED_MEMORY_OBJECTS) && defined(CONFIG_POSIX_SYNCHRONIZED_IO))
+#define _XOPEN_REALTIME _XOPEN_VERSION
+#endif
 /* #define _XOPEN_REALTIME_THREADS (-1L) */
 /* #define _XOPEN_SHM (-1L) */
 
diff --git a/lib/posix/options/CMakeLists.txt b/lib/posix/options/CMakeLists.txt
index b6e9d0bad4e209..f9b465d8a2b51e 100644
--- a/lib/posix/options/CMakeLists.txt
+++ b/lib/posix/options/CMakeLists.txt
@@ -75,10 +75,6 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_FILE_SYSTEM_R)
   zephyr_library_sources_ifdef(CONFIG_POSIX_FILE_SYSTEM_R file_system_r.c)
 endif()
 
-zephyr_library_sources_ifdef(CONFIG_POSIX_FSYNC fsync.c)
-zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK mlockall.c)
-zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK_RANGE mlock.c)
-
 if (NOT CONFIG_TC_PROVIDES_POSIX_MEMORY_PROTECTION)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MEMORY_PROTECTION mprotect.c)
 endif()
@@ -87,8 +83,6 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_MAPPED_FILES)
   zephyr_library_sources_ifdef(CONFIG_POSIX_MAPPED_FILES mmap.c)
 endif()
 
-zephyr_library_sources_ifdef(CONFIG_POSIX_MESSAGE_PASSING mqueue.c)
-
 if (NOT CONFIG_TC_PROVIDES_POSIX_MULTI_PROCESS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_MULTI_PROCESS
     sleep.c
@@ -100,10 +94,6 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_NETWORKING)
   zephyr_library_sources_ifdef(CONFIG_POSIX_NETWORKING net.c)
 endif()
 
-if (NOT CONFIG_TC_PROVIDES_POSIX_SHARED_MEMORY_OBJECTS)
-  zephyr_library_sources_ifdef(CONFIG_POSIX_SHARED_MEMORY_OBJECTS shm.c)
-endif()
-
 if (NOT CONFIG_TC_PROVIDES_POSIX_SIGNALS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_SIGNALS signal.c ${STRSIGNAL_TABLE_H})
 endif()
@@ -129,8 +119,6 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_TIMERS)
   )
 endif()
 
-zephyr_library_sources_ifdef(CONFIG_POSIX_PRIORITY_SCHEDULING sched.c)
-
 if (NOT CONFIG_TC_PROVIDES_POSIX_READER_WRITER_LOCKS)
   # Note: the Option is _POSIX_READER_WRITER_LOCKS, while the Option Group is POSIX_RW_LOCKS.
   # We have opted to use POSIX_READER_WRITER_LOCKS here to match the Option name.
@@ -154,6 +142,15 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_THREADS)
   )
 endif()
 
+if (NOT CONFIG_TC_PROVIDES_XSI_REALTIME)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_FSYNC fsync.c)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK mlockall.c)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK_RANGE mlock.c)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_MESSAGE_PASSING mqueue.c)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_PRIORITY_SCHEDULING sched.c)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_SHARED_MEMORY_OBJECTS shm.c)
+endif()
+
 zephyr_library_sources_ifdef(CONFIG_XOPEN_STREAMS stropts.c)
 
 if (NOT CONFIG_TC_PROVIDES_XSI_SYSTEM_LOGGING)
diff --git a/lib/posix/options/Kconfig b/lib/posix/options/Kconfig
index 6eef8b804a71d1..15d7f2233e630e 100644
--- a/lib/posix/options/Kconfig
+++ b/lib/posix/options/Kconfig
@@ -32,6 +32,7 @@ rsource "Kconfig.timer"
 
 menu "X/Open system interfaces"
 
+rsource "Kconfig.xsi_realtime"
 rsource "Kconfig.xsi_single_process"
 rsource "Kconfig.xsi_streams"
 rsource "Kconfig.xsi_system_logging"
diff --git a/lib/posix/options/Kconfig.toolchain b/lib/posix/options/Kconfig.toolchain
index 30f274067e197d..e328a030879447 100644
--- a/lib/posix/options/Kconfig.toolchain
+++ b/lib/posix/options/Kconfig.toolchain
@@ -135,9 +135,6 @@ config TC_PROVIDES_POSIX_READER_WRITER_LOCKS
 config TC_PROVIDES_POSIX_SEMAPHORES
 	bool
 
-config TC_PROVIDES_POSIX_SHARED_MEMORY_OBJECTS
-	bool
-
 config TC_PROVIDES_POSIX_SHELL_FUNC
 	bool
 
@@ -215,6 +212,9 @@ config TC_PROVIDES_XSI_MATH
 config TC_PROVIDES_XSI_MULTI_PROCESS
 	bool
 
+config TC_PROVIDES_XSI_REALTIME
+	bool
+
 config TC_PROVIDES_XSI_SIGNALS
 	bool
 
diff --git a/lib/posix/options/Kconfig.xsi_realtime b/lib/posix/options/Kconfig.xsi_realtime
new file mode 100644
index 00000000000000..4c232b77a1dd2c
--- /dev/null
+++ b/lib/posix/options/Kconfig.xsi_realtime
@@ -0,0 +1,28 @@
+# Copyright (c) 2024 Tenstorrent AI ULC
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config XSI_REALTIME
+	bool "X/Open realtime"
+	select POSIX_FSYNC
+	select POSIX_MEMLOCK
+	select POSIX_MEMLOCK_RANGE
+	select POSIX_MESSAGE_PASSING
+	# Not yet implemented, but optional
+	# imply POSIX_PRIORITIZED_IO
+	select POSIX_PRIORITY_SCHEDULING
+	select POSIX_SHARED_MEMORY_OBJECTS
+	select POSIX_SYNCHRONIZED_IO
+	help
+	  Select 'y' here and the following functions will be provided:
+
+	  fsync(), mlockall(), munlockall(), mlock(), munlock(), mq_close(), mq_getattr(), mq_notify(),
+	  mq_open(), mq_receive(), mq_send(), mq_setattr(), mq_unlink(), sched_get_priority_max(),
+	  sched_get_priority_min(), sched_getparam(), sched_getscheduler(), sched_rr_get_interval(),
+	  sched_setparam(), sched_setscheduler(), sched_yield(), mmap(), munmap(), shm_open(),
+	  shm_unlink()
+
+	  The functions fsync(), fdatasync(), and open() will provide synchronized I/O capability.
+
+	  For more information, please see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap02.html