Index: lib/libthr/tests/Makefile
===================================================================
--- lib/libthr/tests/Makefile
+++ lib/libthr/tests/Makefile
@@ -4,6 +4,8 @@
 
 TESTSRC=	${SRCTOP}/contrib/netbsd-tests/lib/libpthread
 
+ATF_TESTS_C=	stack_test
+
 # TODO: t_name (missing pthread_getname_np support in FreeBSD)
 NETBSD_ATF_TESTS_C=	barrier_test
 NETBSD_ATF_TESTS_C+=	cond_test
Index: lib/libthr/tests/stack_test.c
===================================================================
--- /dev/null
+++ lib/libthr/tests/stack_test.c
@@ -0,0 +1,70 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 The FreeBSD Foundation
+ *
+ * This software was developed by Mark Johnston 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <limits.h>
+#include <pthread.h>
+
+#include <atf-c.h>
+
+static void *
+emptyfn(void *arg __unused)
+{
+
+	return (NULL);
+}
+
+/*
+ * Make sure that a thread can start and exit when using the minimum stack size.
+ */
+ATF_TC_WITHOUT_HEAD(stack__min_stack_size);
+ATF_TC_BODY(stack__min_stack_size, tc)
+{
+	pthread_t t;
+	pthread_attr_t attr;
+	int error;
+
+	error = pthread_attr_init(&attr);
+	ATF_REQUIRE(error == 0);
+	error = pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
+	ATF_REQUIRE(error == 0);
+	error = pthread_create(&t, &attr, emptyfn, NULL);
+	ATF_REQUIRE(error == 0);
+	error = pthread_join(t, NULL);
+	ATF_REQUIRE(error == 0);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, stack__min_stack_size);
+}
Index: sys/x86/include/_limits.h
===================================================================
--- sys/x86/include/_limits.h
+++ sys/x86/include/_limits.h
@@ -98,6 +98,10 @@
 #define	__WORD_BIT	32
 
 /* Minimum signal stack size. */
+#ifdef __LP64__
+#define	__MINSIGSTKSZ	(1024 * 4)
+#else
 #define	__MINSIGSTKSZ	(512 * 4)
+#endif
 
 #endif /* !_MACHINE__LIMITS_H_ */