diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index e9566e028a..bc14f20274 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -109,7 +109,7 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
tst-tgkill tst-sysvsem-linux tst-sysvmsg-linux tst-sysvshm-linux \
tst-timerfd tst-ppoll \
tst-clock_adjtime tst-adjtimex tst-ntp_adjtime tst-ntp_gettime \
- tst-ntp_gettimex tst-sigtimedwait
+ tst-ntp_gettimex tst-sigtimedwait tst-misalign-clone
# Test for the symbol version of fcntl that was replaced in glibc 2.28.
ifeq ($(have-GLIBC_2.27)$(build-shared),yesyes)
diff --git a/sysdeps/unix/sysv/linux/tst-misalign-clone.c b/sysdeps/unix/sysv/linux/tst-misalign-clone.c
new file mode 100644
index 0000000000..60f0ed0839
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-misalign-clone.c
@@ -0,0 +1,96 @@
+/* Verify that the clone wrapper properly aligns the child stack.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ . */
+
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+static int
+check_stack_alignment (void *arg)
+{
+ bool ok = true;
+
+ puts ("in f");
+
+ if (TEST_STACK_ALIGN ())
+ ok = false;
+
+ return ok ? 0 : 1;
+}
+
+static int
+do_test (void)
+{
+ puts ("in do_test");
+
+ if (TEST_STACK_ALIGN ())
+ FAIL_EXIT1 ("stack isn't aligned\n");
+
+#ifdef __ia64__
+# define STACK_SIZE (256 * 1024)
+#else
+# define STACK_SIZE (128 * 1024)
+#endif
+
+ char st[STACK_SIZE + 1];
+ /* NB: Align child stack to 1 byte. */
+ char *stack = PTR_ALIGN_UP (&st[0], 2) + 1;
+
+#ifdef __ia64__
+ extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
+ size_t __child_stack_size, int __flags,
+ void *__arg, ...);
+ pid_t p = __clone2 (check_stack_alignment, stack, STACK_SIZE, 0, 0);
+#else
+# if _STACK_GROWS_DOWN
+ pid_t p = clone (check_stack_alignment, stack + STACK_SIZE, 0, 0);
+# elif _STACK_GROWS_UP
+ pid_t p = clone (check_stack_alignment, stack, 0, 0);
+# else
+# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
+# endif
+#endif
+
+ /* Clone must not fail. */
+ TEST_VERIFY_EXIT (p != -1);
+
+ int e;
+ xwaitpid (p, &e, __WCLONE);
+ if (!WIFEXITED (e))
+ {
+ if (WIFSIGNALED (e))
+ printf ("died from signal %s\n", strsignal (WTERMSIG (e)));
+ FAIL_EXIT1 ("process did not terminate correctly");
+ }
+
+ if (WEXITSTATUS (e) != 0)
+ FAIL_EXIT1 ("exit code %d", WEXITSTATUS (e));
+
+ return 0;
+}
+
+#include
diff --git a/sysdeps/unix/sysv/linux/x86_64/clone.S b/sysdeps/unix/sysv/linux/x86_64/clone.S
index 31ac12da0c..7418154c4b 100644
--- a/sysdeps/unix/sysv/linux/x86_64/clone.S
+++ b/sysdeps/unix/sysv/linux/x86_64/clone.S
@@ -54,12 +54,15 @@ ENTRY (__clone)
movq $-EINVAL,%rax
testq %rdi,%rdi /* no NULL function pointers */
jz SYSCALL_ERROR_LABEL
- testq %rsi,%rsi /* no NULL stack pointers */
- jz SYSCALL_ERROR_LABEL
+
+ /* Align stack to 16 bytes per the x86-64 psABI. */
+ andq $-16, %rsi
+ jz SYSCALL_ERROR_LABEL /* no NULL stack pointers */
/* Insert the argument onto the new stack. */
+ movq %rcx,-8(%rsi)
+
subq $16,%rsi
- movq %rcx,8(%rsi)
/* Save the function pointer. It will be popped off in the
child. */