diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 11b09345bc..9bcd38a732 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -118,6 +118,14 @@ endif
 
 tests-internal += tst-sigcontext-get_pc
 
+tests-clone-internal = \
+  tst-align-clone-internal \
+  tst-clone2-internal \
+  tst-clone3-internal \
+  tst-getpid1-internal
+tests-internal += $(tests-clone-internal)
+tests-static += $(tests-clone-internal)
+
 CFLAGS-tst-sigcontext-get_pc.c = -fasynchronous-unwind-tables
 
 # Generate the list of SYS_* macros for the system calls (__NR_*
diff --git a/sysdeps/unix/sysv/linux/tst-align-clone-internal.c b/sysdeps/unix/sysv/linux/tst-align-clone-internal.c
new file mode 100644
index 0000000000..0e5307a033
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-align-clone-internal.c
@@ -0,0 +1,86 @@
+/* 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sched.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <tst-stack-align.h>
+#include <clone_internal.h>
+#include <support/xunistd.h>
+
+static int
+f (void *arg)
+{
+  bool ok = true;
+
+  puts ("in f");
+
+  if (TEST_STACK_ALIGN ())
+    ok = false;
+
+  return ok ? 0 : 1;
+}
+
+static int
+do_test (void)
+{
+  bool ok = true;
+
+  puts ("in main");
+
+  if (TEST_STACK_ALIGN ())
+    ok = false;
+
+#ifdef __ia64__
+# define STACK_SIZE 256 * 1024
+#else
+# define STACK_SIZE 128 * 1024
+#endif
+  char st[STACK_SIZE] __attribute__ ((aligned));
+  struct clone_args clone_args =
+    {
+      .stack = (uintptr_t) st,
+      .stack_size = sizeof (st),
+    };
+  pid_t p = __clone_internal (&clone_args, f, 0);
+  if (p == -1)
+    {
+      printf("clone failed: %m\n");
+      return 1;
+    }
+
+  int e;
+  xwaitpid (p, &e, __WCLONE);
+  if (!WIFEXITED (e))
+    {
+      if (WIFSIGNALED (e))
+	printf ("died from signal %s\n", strsignal (WTERMSIG (e)));
+      else
+	puts ("did not terminate correctly");
+      return 1;
+    }
+  if (WEXITSTATUS (e) != 0)
+    ok = false;
+
+  return ok ? 0 : 1;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/tst-clone2-internal.c b/sysdeps/unix/sysv/linux/tst-clone2-internal.c
new file mode 100644
index 0000000000..b8917fe713
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-clone2-internal.c
@@ -0,0 +1,137 @@
+/* Test if CLONE_VM does not change pthread pid/tid field (BZ #19957)
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sched.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <clone_internal.h>
+#include <support/xunistd.h>
+#include <support/check.h>
+
+static int sig;
+static int pipefd[2];
+
+static int
+f (void *a)
+{
+  close (pipefd[0]);
+
+  pid_t ppid = getppid ();
+  pid_t pid = getpid ();
+  pid_t tid = gettid ();
+
+  if (write (pipefd[1], &ppid, sizeof ppid) != sizeof (ppid))
+    FAIL_EXIT1 ("write ppid failed\n");
+  if (write (pipefd[1], &pid, sizeof pid) != sizeof (pid))
+    FAIL_EXIT1 ("write pid failed\n");
+  if (write (pipefd[1], &tid, sizeof tid) != sizeof (tid))
+    FAIL_EXIT1 ("write tid failed\n");
+
+  return 0;
+}
+
+
+static int
+do_test (void)
+{
+  sig = SIGRTMIN;
+  sigset_t ss;
+  sigemptyset (&ss);
+  sigaddset (&ss, sig);
+  if (sigprocmask (SIG_BLOCK, &ss, NULL) != 0)
+    FAIL_EXIT1 ("sigprocmask failed: %m");
+
+  if (pipe2 (pipefd, O_CLOEXEC))
+    FAIL_EXIT1 ("pipe failed: %m");
+
+#ifdef __ia64__
+# define STACK_SIZE 256 * 1024
+#else
+# define STACK_SIZE 128 * 1024
+#endif
+  char st[STACK_SIZE] __attribute__ ((aligned));
+  struct clone_args clone_args =
+    {
+      .stack = (uintptr_t) st,
+      .stack_size = sizeof (st),
+    };
+  pid_t p = __clone_internal (&clone_args, f, 0);
+
+  close (pipefd[1]);
+
+  if (p == -1)
+    FAIL_EXIT1("clone failed: %m");
+
+  pid_t ppid, pid, tid;
+  if (read (pipefd[0], &ppid, sizeof pid) != sizeof pid)
+    {
+      kill (p, SIGKILL);
+      FAIL_EXIT1 ("read ppid failed: %m");
+    }
+  if (read (pipefd[0], &pid, sizeof pid) != sizeof pid)
+    {
+      kill (p, SIGKILL);
+      FAIL_EXIT1 ("read pid failed: %m");
+    }
+  if (read (pipefd[0], &tid, sizeof tid) != sizeof tid)
+    {
+      kill (p, SIGKILL);
+      FAIL_EXIT1 ("read tid failed: %m");
+    }
+
+  close (pipefd[0]);
+
+  int ret = 0;
+
+  pid_t own_pid = getpid ();
+  pid_t own_tid = syscall (__NR_gettid);
+
+  /* Some sanity checks for clone syscall: returned ppid should be current
+     pid and both returned tid/pid should be different from current one.  */
+  if ((ppid != own_pid) || (pid == own_pid) || (tid == own_tid))
+    FAIL_RET ("ppid=%i pid=%i tid=%i | own_pid=%i own_tid=%i",
+	      (int)ppid, (int)pid, (int)tid, (int)own_pid, (int)own_tid);
+
+  int e;
+  xwaitpid (p, &e, __WCLONE);
+  if (!WIFEXITED (e))
+    {
+      if (WIFSIGNALED (e))
+	printf ("died from signal %s\n", strsignal (WTERMSIG (e)));
+      else
+	puts ("did not terminate correctly");
+      exit (EXIT_FAILURE);
+    }
+  if (WEXITSTATUS (e) != 0)
+    FAIL_EXIT1 ("exit code %d", WEXITSTATUS (e));
+
+  return ret;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/tst-clone3-internal.c b/sysdeps/unix/sysv/linux/tst-clone3-internal.c
new file mode 100644
index 0000000000..2bdbc571e6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-clone3-internal.c
@@ -0,0 +1,99 @@
+/* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512)
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <sched.h>
+#include <signal.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <linux/futex.h>
+#include <support/check.h>
+#include <stdatomic.h>
+#include <clone_internal.h>
+
+/* Test if clone call with CLONE_THREAD does not call exit_group.  The 'f'
+   function returns '1', which will be used by clone thread to call the
+   'exit' syscall directly.  If _exit is used instead, exit_group will be
+   used and thus the thread group will finish with return value of '1'
+   (where '2' from main thread is expected.).  */
+
+static int
+f (void *a)
+{
+  return 1;
+}
+
+/* Futex wait for TID argument, similar to pthread_join internal
+   implementation.  */
+#define wait_tid(ctid_ptr, ctid_val)					\
+  do {									\
+    __typeof (*(ctid_ptr)) __tid;					\
+    /* We need acquire MO here so that we synchronize with the		\
+       kernel's store to 0 when the clone terminates.  */		\
+    while ((__tid = atomic_load_explicit (ctid_ptr,			\
+					  memory_order_acquire)) != 0)	\
+      futex_wait (ctid_ptr, ctid_val);					\
+  } while (0)
+
+static inline int
+futex_wait (int *futexp, int val)
+{
+#ifdef __NR_futex
+  return syscall (__NR_futex, futexp, FUTEX_WAIT, val);
+#else
+  return syscall (__NR_futex_time64, futexp, FUTEX_WAIT, val);
+#endif
+}
+
+static int
+do_test (void)
+{
+  char st[1024] __attribute__ ((aligned));
+  int clone_flags = CLONE_THREAD;
+  /* Minimum required flags to used along with CLONE_THREAD.  */
+  clone_flags |= CLONE_VM | CLONE_SIGHAND;
+  /* We will used ctid to call on futex to wait for thread exit.  */
+  clone_flags |= CLONE_CHILD_CLEARTID;
+  /* Initialize with a known value.  ctid is set to zero by the kernel after the
+     cloned thread has exited.  */
+#define CTID_INIT_VAL 1
+  pid_t ctid = CTID_INIT_VAL;
+  pid_t tid;
+
+  struct clone_args clone_args =
+    {
+      .flags = clone_flags & ~CSIGNAL,
+      .exit_signal = clone_flags & CSIGNAL,
+      .stack = (uintptr_t) st,
+      .stack_size = sizeof (st),
+      .child_tid = (uintptr_t) &ctid,
+    };
+  tid = __clone_internal (&clone_args, f, NULL);
+  if (tid == -1)
+    FAIL_EXIT1 ("clone failed: %m");
+
+  wait_tid (&ctid, CTID_INIT_VAL);
+
+  return 2;
+}
+
+#define EXPECTED_STATUS 2
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/tst-getpid1-internal.c b/sysdeps/unix/sysv/linux/tst-getpid1-internal.c
new file mode 100644
index 0000000000..5ce091168e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-getpid1-internal.c
@@ -0,0 +1,132 @@
+/* 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sched.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <clone_internal.h>
+#include <support/xunistd.h>
+
+#ifndef TEST_CLONE_FLAGS
+#define TEST_CLONE_FLAGS 0
+#endif
+
+static int sig;
+
+static int
+f (void *a)
+{
+  puts ("in f");
+  union sigval sival;
+  sival.sival_int = getpid ();
+  printf ("pid = %d\n", sival.sival_int);
+  if (sigqueue (getppid (), sig, sival) != 0)
+    return 1;
+  return 0;
+}
+
+
+static int
+do_test (void)
+{
+  int mypid = getpid ();
+
+  sig = SIGRTMIN;
+  sigset_t ss;
+  sigemptyset (&ss);
+  sigaddset (&ss, sig);
+  if (sigprocmask (SIG_BLOCK, &ss, NULL) != 0)
+    {
+      printf ("sigprocmask failed: %m\n");
+      return 1;
+    }
+
+#ifdef __ia64__
+# define STACK_SIZE 256 * 1024
+#else
+# define STACK_SIZE 128 * 1024
+#endif
+  char st[STACK_SIZE] __attribute__ ((aligned));
+  struct clone_args clone_args =
+    {
+      .flags = TEST_CLONE_FLAGS & ~CSIGNAL,
+      .exit_signal = TEST_CLONE_FLAGS & CSIGNAL,
+      .stack = (uintptr_t) st,
+      .stack_size = sizeof (st),
+    };
+  pid_t p = __clone_internal (&clone_args, f, 0);
+  if (p == -1)
+    {
+      printf("clone failed: %m\n");
+      return 1;
+    }
+  printf ("new thread: %d\n", (int) p);
+
+  siginfo_t si;
+  do
+    if (sigwaitinfo (&ss, &si) < 0)
+      {
+	printf("sigwaitinfo failed: %m\n");
+	kill (p, SIGKILL);
+	return 1;
+      }
+  while  (si.si_signo != sig || si.si_code != SI_QUEUE);
+
+  int e;
+  xwaitpid (p, &e, __WCLONE);
+  if (!WIFEXITED (e))
+    {
+      if (WIFSIGNALED (e))
+	printf ("died from signal %s\n", strsignal (WTERMSIG (e)));
+      else
+	puts ("did not terminate correctly");
+      return 1;
+    }
+  if (WEXITSTATUS (e) != 0)
+    {
+      printf ("exit code %d\n", WEXITSTATUS (e));
+      return 1;
+    }
+
+  if (si.si_int != (int) p)
+    {
+      printf ("expected PID %d, got si_int %d\n", (int) p, si.si_int);
+      kill (p, SIGKILL);
+      return 1;
+    }
+
+  if (si.si_pid != p)
+    {
+      printf ("expected PID %d, got si_pid %d\n", (int) p, (int) si.si_pid);
+      kill (p, SIGKILL);
+      return 1;
+    }
+
+  if (getpid () != mypid)
+    {
+      puts ("my PID changed");
+      return 1;
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>
