diff --git a/include/pthread.h b/include/pthread.h
index feb094c39fce..311211cb48f1 100644
--- a/include/pthread.h
+++ b/include/pthread.h
@@ -43,6 +43,9 @@
 #include <machine/_limits.h>
 #include <sys/_types.h>
 #include <sys/_sigset.h>
+#if __BSD_VISIBLE
+#include <sys/_sigval.h>
+#endif
 #include <sched.h>
 #include <time.h>
 
@@ -302,6 +305,10 @@ void		pthread_yield(void);
 
 int		pthread_getname_np(pthread_t, char *, size_t);
 int		pthread_setname_np(pthread_t, const char *);
+
+int		pthread_sigqueue(pthread_t thread, int sig,
+		    const union sigval value);
+
 #endif
 
 int		pthread_mutexattr_getprioceiling(
diff --git a/lib/libthr/pthread.map b/lib/libthr/pthread.map
index aa9abb7e6114..f75ef4c9135e 100644
--- a/lib/libthr/pthread.map
+++ b/lib/libthr/pthread.map
@@ -337,3 +337,7 @@ FBSD_1.6 {
 	 pthread_peekjoin_np;
 	 pthread_setname_np;
 };
+
+FBSD_1.8 {
+	 pthread_sigqueue;
+};
diff --git a/lib/libthr/thread/Makefile.inc b/lib/libthr/thread/Makefile.inc
index 33b95e9dd76d..c75322d6be95 100644
--- a/lib/libthr/thread/Makefile.inc
+++ b/lib/libthr/thread/Makefile.inc
@@ -47,6 +47,7 @@ SRCS+= \
 	thr_setprio.c \
 	thr_setschedparam.c \
 	thr_sig.c \
+	thr_sigqueue.c \
 	thr_single_np.c \
 	thr_sleepq.c \
 	thr_spec.c \
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index e590fb0c1e7a..f89941f96c78 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -1102,6 +1102,7 @@ int __Tthr_mutex_lock(pthread_mutex_t *);
 int __Tthr_mutex_trylock(pthread_mutex_t *);
 bool __thr_get_main_stack_base(char **base);
 bool __thr_get_main_stack_lim(size_t *lim);
+int _Tthr_sigqueue(pthread_t pthread, int sig, const union sigval value);
 
 __END_DECLS
 __NULLABILITY_PRAGMA_POP
diff --git a/lib/libthr/thread/thr_sigqueue.c b/lib/libthr/thread/thr_sigqueue.c
new file mode 100644
index 000000000000..6f7ad8c63bad
--- /dev/null
+++ b/lib/libthr/thread/thr_sigqueue.c
@@ -0,0 +1,79 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
+ * All rights reserved.
+ *
+ * Copyright 2024 The FreeBSD Foundation
+ *
+ * Portions of this software were developed by Konstantin Belousov
+ * <kib@FreeBSD.org> under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "namespace.h"
+#include <errno.h>
+#include <signal.h>
+#include <pthread.h>
+#include "un-namespace.h"
+
+#include "thr_private.h"
+
+__weak_reference(_Tthr_sigqueue, _pthread_sigqueue);
+__weak_reference(_Tthr_sigqueue, pthread_sigqueue);
+
+int
+_Tthr_sigqueue(pthread_t pthread, int sig, const union sigval value)
+{
+	struct pthread *curthread;
+	int e, ret;
+
+	if (sig < 0 || sig > _SIG_MAXSIG)
+		return (EINVAL);
+
+	curthread = _get_curthread();
+	ret = 0;
+
+	if (curthread == pthread) {
+		if (sig > 0) {
+			e = sigqueue(pthread->tid, sig | __SIGQUEUE_TID,
+			    value);
+			if (e == -1)
+				ret = errno;
+		}
+	} else if ((ret = _thr_find_thread(curthread, pthread,
+	    0)) == 0) {
+		if (sig > 0) {
+			e = sigqueue(pthread->tid, sig | __SIGQUEUE_TID,
+			    value);
+			if (e == -1)
+				ret = errno;
+		}
+		THR_THREAD_UNLOCK(curthread, pthread);
+	}
+
+	return (ret);
+}