diff --git a/NEWS b/NEWS
index 190b0ddb57..1d1c193743 100644
--- a/NEWS
+++ b/NEWS
@@ -51,6 +51,12 @@ Major new features:
   pthread_attr_setperthreadfs_np and pthread_attr_getperthreadfs_np have
   been added in support of that.
 
+* On Linux, threads can now be created in such a way that they retain
+  per-thread user and group IDs.  (This has always been the way how the
+  Linux kernel implements threads.)  The functions
+  pthread_attr_setperthreadids_np and pthread_attr_getperthreadids_np have
+  been added in support of that.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.tune tunable namespace has been renamed to glibc.cpu and the
diff --git a/nptl/Makefile b/nptl/Makefile
index 8a071af5c7..7e82f0bdbf 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -31,7 +31,8 @@ routines = alloca_cutoff forward libc-lowlevellock libc-cancellation \
 	   libc-cleanup libc_pthread_init libc_multiple_threads \
 	   register-atfork pthread_atfork pthread_self thrd_current \
 	   thrd_equal thrd_sleep thrd_yield \
-	   pthread_attr_setperthreadfs_np pthread_attr_getperthreadfs_np
+	   pthread_attr_setperthreadfs_np pthread_attr_getperthreadfs_np \
+	   pthread_attr_setperthreadids_np pthread_attr_getperthreadids_np
 shared-only-routines = forward
 static-only-routines = pthread_atfork
 
@@ -328,7 +329,8 @@ tests-internal := tst-rwlock19 tst-rwlock20 \
 		  tst-mutexpi8 tst-mutexpi8-static
 
 xtests = tst-setuid1 tst-setuid1-static tst-setuid2 \
-	tst-mutexpp1 tst-mutexpp6 tst-mutexpp10
+	tst-mutexpp1 tst-mutexpp6 tst-mutexpp10 \
+	tst-pthread-perthreadids
 test-srcs = tst-oddstacklimit
 
 # Test expected to fail on most targets (except x86_64) due to bug
diff --git a/nptl/Versions b/nptl/Versions
index ba71f85411..95490322d6 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -35,6 +35,8 @@ libc {
   GLIBC_2.29 {
     pthread_attr_setperthreadfs_np;
     pthread_attr_getperthreadfs_np;
+    pthread_attr_setperthreadids_np;
+    pthread_attr_getperthreadids_np;
   }
   GLIBC_PRIVATE {
     __libc_alloca_cutoff;
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 04e3f08465..d4c25a951f 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -1114,6 +1114,14 @@ __nptl_setxid_error (struct xid_command *cmdp, int error)
   while (atomic_compare_and_exchange_bool_acq (&cmdp->error, error, -1));
 }
 
+/* The current thread and threads with per-thread user and group IDs
+   are not part of the setxid broadcast.  */
+static inline bool
+thread_excluded_from_setxid_broadcast (struct pthread *self, struct pthread *t)
+{
+  return t == self || (t->flags & ATTR_FLAG_PERTHREADIDS);
+}
+
 int
 attribute_hidden
 __nptl_setxid (struct xid_command *cmdp)
@@ -1127,13 +1135,14 @@ __nptl_setxid (struct xid_command *cmdp)
   cmdp->error = -1;
 
   struct pthread *self = THREAD_SELF;
+  assert (!nptl_current_thread_has_separate_ids ());
 
   /* Iterate over the list with system-allocated threads first.  */
   list_t *runp;
   list_for_each (runp, &stack_used)
     {
       struct pthread *t = list_entry (runp, struct pthread, list);
-      if (t == self)
+      if (thread_excluded_from_setxid_broadcast (self, t))
 	continue;
 
       setxid_mark_thread (cmdp, t);
@@ -1143,7 +1152,7 @@ __nptl_setxid (struct xid_command *cmdp)
   list_for_each (runp, &__stack_user)
     {
       struct pthread *t = list_entry (runp, struct pthread, list);
-      if (t == self)
+      if (thread_excluded_from_setxid_broadcast (self, t))
 	continue;
 
       setxid_mark_thread (cmdp, t);
@@ -1159,7 +1168,7 @@ __nptl_setxid (struct xid_command *cmdp)
       list_for_each (runp, &stack_used)
 	{
 	  struct pthread *t = list_entry (runp, struct pthread, list);
-	  if (t == self)
+	  if (thread_excluded_from_setxid_broadcast (self, t))
 	    continue;
 
 	  signalled += setxid_signal_thread (cmdp, t);
@@ -1168,7 +1177,7 @@ __nptl_setxid (struct xid_command *cmdp)
       list_for_each (runp, &__stack_user)
 	{
 	  struct pthread *t = list_entry (runp, struct pthread, list);
-	  if (t == self)
+	  if (thread_excluded_from_setxid_broadcast (self, t))
 	    continue;
 
 	  signalled += setxid_signal_thread (cmdp, t);
@@ -1189,7 +1198,7 @@ __nptl_setxid (struct xid_command *cmdp)
   list_for_each (runp, &stack_used)
     {
       struct pthread *t = list_entry (runp, struct pthread, list);
-      if (t == self)
+      if (thread_excluded_from_setxid_broadcast (self, t))
 	continue;
 
       setxid_unmark_thread (cmdp, t);
@@ -1198,7 +1207,7 @@ __nptl_setxid (struct xid_command *cmdp)
   list_for_each (runp, &__stack_user)
     {
       struct pthread *t = list_entry (runp, struct pthread, list);
-      if (t == self)
+      if (thread_excluded_from_setxid_broadcast (self, t))
 	continue;
 
       setxid_unmark_thread (cmdp, t);
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 7f16ba9800..7a1f965d9e 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -655,6 +655,14 @@ check_stacksize_attr (size_t st)
   return EINVAL;
 }
 
+/* Return true if the current thread has per-thread user and group
+   IDS.  */
+static inline bool
+nptl_current_thread_has_separate_ids (void)
+{
+  return THREAD_SELF->flags & ATTR_FLAG_PERTHREADIDS;
+}
+
 #define ASSERT_TYPE_SIZE(type, size) 					\
   _Static_assert (sizeof (type) == size,				\
 		  "sizeof (" #type ") != " #size)
diff --git a/nptl/pthread_attr_getperthreadids_np.c b/nptl/pthread_attr_getperthreadids_np.c
new file mode 100644
index 0000000000..cfadfb3bed
--- /dev/null
+++ b/nptl/pthread_attr_getperthreadids_np.c
@@ -0,0 +1,27 @@
+/* Read the per-thread user/group IDs flag in thread attributes.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <internaltypes.h>
+
+int
+pthread_attr_getperthreadids_np (const pthread_attr_t *attr)
+{
+  struct pthread_attr *iattr = (struct pthread_attr *) attr;
+  return (iattr->flags & ATTR_FLAG_PERTHREADIDS) != 0;
+}
diff --git a/nptl/pthread_attr_setperthreadids_np.c b/nptl/pthread_attr_setperthreadids_np.c
new file mode 100644
index 0000000000..84d68e0e4f
--- /dev/null
+++ b/nptl/pthread_attr_setperthreadids_np.c
@@ -0,0 +1,30 @@
+/* Change the per-thread user/group IDs flag in thread attributes.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <internaltypes.h>
+
+void
+pthread_attr_setperthreadids_np (pthread_attr_t *attr, int enabled)
+{
+  struct pthread_attr *iattr = (struct pthread_attr *) attr;
+  if (enabled)
+    iattr->flags |= ATTR_FLAG_PERTHREADIDS;
+  else
+    iattr->flags &= ~ATTR_FLAG_PERTHREADIDS;
+}
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index fe75d04113..cf9dae201b 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -700,8 +700,8 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
 
   /* Copy the thread attribute flags.  */
   struct pthread *self = THREAD_SELF;
-  pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
-	       | (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)));
+  pd->flags = ((iattr->flags & ~ATTR_FLAGS_IGNORED_ATTR)
+	       | (self->flags & ATTR_FLAGS_INHERITED));
 
   /* Initialize the field for the ID of the thread which is waiting
      for us.  This is a self-reference in case the thread is created
diff --git a/nptl/tst-pthread-perthreadids.c b/nptl/tst-pthread-perthreadids.c
new file mode 100644
index 0000000000..ad021e1255
--- /dev/null
+++ b/nptl/tst-pthread-perthreadids.c
@@ -0,0 +1,426 @@
+/* Test per-thread user and group IDs.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <errno.h>
+#include <grp.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+#include <support/xthread.h>
+#include <support/xunistd.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+enum operation
+{
+ OP_NONE,
+ OP_SETUID,
+ OP_SETEUID,
+ OP_SETREUID,
+ OP_SETRESUID,
+ OP_SETGID,
+ OP_SETEGID,
+ OP_SETREGID,
+ OP_SETRESGID,
+ OP_SETGROUPS,
+};
+
+static const char *
+operation_string (enum operation op)
+{
+  switch (op)
+    {
+    case OP_NONE:
+      return "<none>";
+    case OP_SETUID:
+      return "OP_SETUID";
+    case OP_SETEUID:
+      return "OP_SETEUID";
+    case OP_SETREUID:
+      return "OP_SETREUID";
+    case OP_SETRESUID:
+      return "OP_SETRESUID";
+    case OP_SETGID:
+      return "OP_SETGID";
+    case OP_SETEGID:
+      return "OP_SETEGID";
+    case OP_SETREGID:
+      return "OP_SETREGID";
+    case OP_SETRESGID:
+      return "OP_SETRESGID";
+    case OP_SETGROUPS:
+      return "OP_SETGROUPS";
+    }
+
+  FAIL_EXIT1 ("invalid operation: %d", (int) op);
+}
+
+struct test_case
+{
+  enum operation op;
+  int args[3];
+
+  /* Expected UIDs and GIDs are only used if the current thread has
+     made changes.  */
+  uid_t expected_uid[3];
+  gid_t expected_gid[3];
+};
+
+static const struct test_case test_cases[] =
+  {
+   { OP_NONE, { 0, }, { 0, 0, 0}, {0, 0, 0} },
+
+   { OP_SETUID, { 1, }, { 1, 1, 1 }, { 0, } },
+   { OP_SETEUID, { 2, }, { 0, 2, }, { 0, } },
+   { OP_SETREUID, { 3, 4, }, { 3, 4, 4 }, { 0, } },
+   { OP_SETRESUID, { 3, 4, 5 }, { 3, 4, 5 }, { 0, } },
+
+   { OP_SETGID, { 6, }, { 0, }, { 6, 6, 6 } },
+   { OP_SETEGID, { 7, }, { 0, }, { 0, 7, } },
+   { OP_SETREGID, { 8, 9, }, { 0, }, { 8, 9, 9 } },
+   { OP_SETRESGID, { 10, 11, 12 }, { 0, }, { 10, 11, 12 } },
+
+   { OP_SETGROUPS, { -1, }, { 0, }, { 0, } },
+   { OP_SETGROUPS, { 13, -1 }, { 0, }, { 0, } },
+   { OP_SETGROUPS, { 13, 14, -1 }, { 0, }, { 0, } },
+   { OP_SETGROUPS, { 13, 14, 15 }, { 0, }, { 0, } },
+
+   /* Final round of checks.  */
+   { OP_NONE, { 0, }, { 0, }, {0, } },
+  };
+
+static size_t
+supplemetary_count (const struct test_case *test)
+{
+  TEST_COMPARE (test->op, OP_SETGROUPS);
+  size_t count = 0;
+  while (count < array_length (test->args))
+    {
+      if (test->args[count] < 0)
+        break;
+      ++count;
+    }
+  return count;
+}
+
+static void
+test_case_run (const struct test_case *test)
+{
+  int ret = -1;
+  switch (test->op)
+    {
+    case OP_NONE:
+      return;
+
+    case OP_SETUID:
+      ret = setuid (test->args[0]);
+      break;
+    case OP_SETEUID:
+      ret = seteuid (test->args[0]);
+      break;
+    case OP_SETREUID:
+      ret = setreuid (test->args[0], test->args[1]);
+      break;
+    case OP_SETRESUID:
+      ret = setresuid (test->args[0], test->args[1], test->args[2]);
+      break;
+
+    case OP_SETGID:
+      ret = setgid (test->args[0]);
+      break;
+    case OP_SETEGID:
+      ret = setegid (test->args[0]);
+      break;
+    case OP_SETREGID:
+      ret = setregid (test->args[0], test->args[1]);
+      break;
+    case OP_SETRESGID:
+      ret = setresgid (test->args[0], test->args[1], test->args[2]);
+      break;
+
+    case OP_SETGROUPS:
+      {
+        gid_t groups[] = { test->args[0], test->args[1], test->args[2] };
+        ret = setgroups (supplemetary_count (test), groups);
+      }
+    }
+
+  if (ret != 0)
+    FAIL_EXIT1 ("%s (%d, %d, %d): %m (%d)",
+                operation_string (test->op),
+                test->args[0], test->args[1], test->args[2], errno);
+}
+
+/* Used to synchronize between threads changing UIDs/GIDs.  */
+static pthread_barrier_t barrier;
+
+/* Used to avoid interleaving the checking phase between threads.  */
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* Argument to the thread.  */
+struct thread_argument
+{
+  size_t thread_index;
+  /* Do not actually perform the operation, only verify the result.
+     Used for threads participating in the setxid broadcast.  */
+  bool suppress_operation;
+
+  /* Run the actual test in a newly created thread, with default
+     attributes.  */
+  bool indirect;
+};
+
+static struct thread_argument *
+create_thread_argument (size_t index, bool suppress, bool indirect)
+{
+  struct thread_argument *result = xmalloc (sizeof (*result));
+  result->thread_index = index;
+  result->suppress_operation = suppress;
+  return result;
+}
+
+static void *
+threadfunc (void *closure)
+{
+  struct thread_argument *arg = closure;
+
+  if (arg->indirect)
+    {
+      arg->indirect = false;
+      xpthread_join (xpthread_create (NULL, threadfunc, arg));
+      return NULL;
+    }
+
+  const struct test_case *expected = &test_cases[0];
+  gid_t expected_supplementary[3] = { -1, -1, -1 };
+  int expected_supplementary_count = 0;
+
+  xpthread_barrier_wait (&barrier);
+
+  for (size_t test_index = 0; test_index < array_length (test_cases);
+       ++test_index)
+    {
+      if (test_index == arg->thread_index)
+        {
+          if (test_verbose > 0)
+            {
+              if (arg->suppress_operation)
+                printf ("info: thread %zu suppressing operation\n",
+                        test_index);
+              else
+                printf ("info: thread %zu performing operation\n",
+                        test_index);
+            }
+          if (!arg->suppress_operation)
+            test_case_run (&test_cases[test_index]);
+
+          expected = &test_cases[test_index];
+          if (test_cases[test_index].op == OP_SETGROUPS)
+            {
+              expected_supplementary_count
+                = supplemetary_count (&test_cases[test_index]);
+              for (int i = 0; i < expected_supplementary_count; ++i)
+                expected_supplementary[i] = test_cases[test_index].args[i];
+            }
+        }
+
+      xpthread_barrier_wait (&barrier);
+
+      xpthread_mutex_lock (&mutex);
+
+      if (test_verbose > 0)
+        printf ("info: checking phase for thread %zu, test %zu\n",
+                arg->thread_index, test_index);
+      uid_t actual_uid[3];
+      xgetresuid (&actual_uid[0], &actual_uid[1], &actual_uid[2]);
+      TEST_COMPARE (actual_uid[0], expected->expected_uid[0]);
+      TEST_COMPARE (actual_uid[1], expected->expected_uid[1]);
+      TEST_COMPARE (actual_uid[2], expected->expected_uid[2]);
+      gid_t actual_gid[3];
+      xgetresgid (&actual_gid[0], &actual_gid[1], &actual_gid[2]);
+      TEST_COMPARE (actual_gid[0], expected->expected_gid[0]);
+      TEST_COMPARE (actual_gid[1], expected->expected_gid[1]);
+      TEST_COMPARE (actual_gid[2], expected->expected_gid[2]);
+
+      gid_t actual_supplementary[3];
+      gid_t actual_supplementary_count
+        = getgroups (array_length (actual_supplementary),
+                     actual_supplementary);
+      TEST_COMPARE (actual_supplementary_count, expected_supplementary_count);
+      if (actual_supplementary_count > 0)
+        TEST_COMPARE (actual_supplementary[0], expected_supplementary[0]);
+      if (actual_supplementary_count > 1)
+        TEST_COMPARE (actual_supplementary[1], expected_supplementary[1]);
+      if (actual_supplementary_count > 2)
+        TEST_COMPARE (actual_supplementary[2], expected_supplementary[2]);
+
+      xpthread_mutex_unlock (&mutex);
+
+      xpthread_barrier_wait (&barrier);
+    }
+
+  free (arg);
+  return NULL;
+}
+
+/* Used to create threads with per-thread user/group IDs.  */
+static pthread_attr_t attr_perthreadids;
+
+/* Test which verifies that per-thread IDs are thread-specific.  */
+static void
+check_perthread (bool indirect)
+{
+  if (test_verbose > 0)
+    printf ("info: testing per-thread IDs, %s indirection\n",
+            indirect ? "with" : "without");
+  /* Main thread and another shared thread are extras.  */
+  xpthread_barrier_init (&barrier, NULL, array_length (test_cases) + 2);
+
+  pthread_t perthread_threads[array_length (test_cases)];
+  /* Use thread index zero for no-op checking.  */
+  pthread_t shared_thread
+    = xpthread_create (NULL, threadfunc,
+                       create_thread_argument (0, false, false));
+  for (size_t i = 0; i < array_length (test_cases); ++i)
+    {
+      struct thread_argument *arg
+        = create_thread_argument (i, false, indirect);
+      perthread_threads[i] = xpthread_create (&attr_perthreadids, threadfunc,
+                                              arg);
+    }
+  /* Use thread index zero for no-op checking.  */
+  threadfunc (create_thread_argument (0, false, false));
+  for (size_t i = 0; i < array_length (test_cases); ++i)
+    xpthread_join (perthread_threads[i]);
+  xpthread_join (shared_thread);
+
+  xpthread_barrier_destroy (&barrier);
+}
+
+/* Closure arguments to the subprocess.  */
+struct subprocess_argument
+{
+  size_t broadcast_test_index;
+  bool broadcast_from_main;
+  bool indirect;
+};
+
+/* Setting the broadcast UID is destructive, so we need to run it in a
+   subprocess.  */
+static void
+subprocess (void *closure)
+{
+  struct subprocess_argument *arg = closure;
+
+  if (test_verbose > 0)
+    printf ("info: testing broadcasting test case %zu,"
+            " %sbroadcasting from main, %s indirection\n",
+            arg->broadcast_test_index,
+            arg->broadcast_from_main ? "" : "not ",
+            arg->indirect ? "with" : "without");
+
+  /* Main thread and two other shared threads are extras.  One
+     per-thread test is skipped, so there are two extra threads.  */
+  xpthread_barrier_init (&barrier, NULL, array_length (test_cases) + 2);
+
+  pthread_t perthread_threads[array_length (test_cases)];
+  /* Use thread index zero for no-op checking.  */
+  pthread_t shared_threads[2];
+  shared_threads[0]
+    = xpthread_create (NULL, threadfunc,
+                       create_thread_argument (arg->broadcast_test_index,
+                                               arg->broadcast_from_main,
+                                               false));
+  shared_threads[1]
+    = xpthread_create (NULL, threadfunc,
+                       create_thread_argument (arg->broadcast_test_index,
+                                               true, false));
+
+  for (size_t i = 0; i < array_length (test_cases); ++i)
+    /* Skip the test which uses broadcasting.  */
+    if (i != arg->broadcast_test_index)
+      perthread_threads[i]
+        = xpthread_create (&attr_perthreadids, threadfunc,
+                           create_thread_argument (i, false, arg->indirect));
+  /* Use thread index zero for no-op checking.  */
+  threadfunc (create_thread_argument (arg->broadcast_test_index,
+                                      !arg->broadcast_from_main, false));
+  for (size_t i = 0; i < array_length (test_cases); ++i)
+    /* Skip the test which uses broadcasting.  */
+    if (i != arg->broadcast_test_index)
+      xpthread_join (perthread_threads[i]);
+  xpthread_join (shared_threads[0]);
+  xpthread_join (shared_threads[1]);
+
+  xpthread_barrier_destroy (&barrier);
+}
+
+static int
+do_test (void)
+{
+  if (setuid (0) != 0)
+    FAIL_EXIT1 ("setuid (0): %m");
+  if (setgid (0) != 0)
+    FAIL_EXIT1 ("setgid (0): %m");
+  if (setgroups (0, NULL) != 0)
+    FAIL_EXIT1 ("setgroups (0, NULL): %m");
+
+  xpthread_attr_init (&attr_perthreadids);
+  TEST_COMPARE (pthread_attr_getperthreadids_np (&attr_perthreadids), 0);
+  pthread_attr_setperthreadids_np (&attr_perthreadids, true);
+  TEST_COMPARE (pthread_attr_getperthreadids_np (&attr_perthreadids), 1);
+  /* The flag is normalized to 1.  */
+  pthread_attr_setperthreadids_np (&attr_perthreadids, 2);
+  TEST_COMPARE (pthread_attr_getperthreadids_np (&attr_perthreadids), 1);
+  pthread_attr_setperthreadids_np (&attr_perthreadids, 0);
+  TEST_COMPARE (pthread_attr_getperthreadids_np (&attr_perthreadids), 0);
+  pthread_attr_setperthreadids_np (&attr_perthreadids, true);
+  TEST_COMPARE (pthread_attr_getperthreadids_np (&attr_perthreadids), 1);
+
+  for (int indirect = 0; indirect < 2; ++indirect)
+    {
+      check_perthread (indirect);
+
+      for (int broadcast_from_main = 0; broadcast_from_main < 2;
+           ++broadcast_from_main)
+        for (size_t broadcast_test_index = 0;
+             broadcast_test_index < array_length (test_cases);
+             ++broadcast_test_index)
+          {
+            struct subprocess_argument arg =
+              {
+               .broadcast_test_index = broadcast_test_index,
+               .broadcast_from_main = broadcast_from_main,
+               .indirect = indirect,
+              };
+            support_isolate_in_subprocess (subprocess, &arg);
+          }
+    }
+
+  xpthread_attr_destroy (&attr_perthreadids);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/Makefile b/support/Makefile
index 2ef8c019b1..230532d728 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -88,6 +88,8 @@ libsupport-routines = \
   xfopen \
   xfork \
   xftruncate \
+  xgetresgid \
+  xgetresuid \
   xgetsockname \
   xlisten \
   xlseek \
diff --git a/support/xgetresgid.c b/support/xgetresgid.c
new file mode 100644
index 0000000000..2e7b413934
--- /dev/null
+++ b/support/xgetresgid.c
@@ -0,0 +1,27 @@
+/* getresgid with error checking.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+
+void
+xgetresgid (gid_t *real, gid_t *effective, gid_t *saved)
+{
+  if (getresgid (real, effective, saved) != 0)
+    FAIL_EXIT1 ("getresgid: %m");
+}
diff --git a/support/xgetresuid.c b/support/xgetresuid.c
new file mode 100644
index 0000000000..0081d1fa78
--- /dev/null
+++ b/support/xgetresuid.c
@@ -0,0 +1,27 @@
+/* getresuid with error checking.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+
+void
+xgetresuid (uid_t *real, uid_t *effective, uid_t *saved)
+{
+  if (getresuid (real, effective, saved) != 0)
+    FAIL_EXIT1 ("getresuid: %m");
+}
diff --git a/support/xunistd.h b/support/xunistd.h
index 13dfa2c0e5..2233aa0386 100644
--- a/support/xunistd.h
+++ b/support/xunistd.h
@@ -46,6 +46,8 @@ long xsysconf (int name);
 long long xlseek (int fd, long long offset, int whence);
 void xftruncate (int fd, long long length);
 void xsymlink (const char *target, const char *linkpath);
+void xgetresuid (uid_t *, uid_t *, uid_t *);
+void xgetresgid (gid_t *, gid_t *, gid_t *);
 
 /* Equivalent of "mkdir -p".  */
 void xmkdirp (const char *, mode_t);
diff --git a/sysdeps/nptl/internaltypes.h b/sysdeps/nptl/internaltypes.h
index 30396cc448..cde8f40503 100644
--- a/sysdeps/nptl/internaltypes.h
+++ b/sysdeps/nptl/internaltypes.h
@@ -49,7 +49,18 @@ struct pthread_attr
 #define ATTR_FLAG_SCHED_SET		0x0020
 #define ATTR_FLAG_POLICY_SET		0x0040
 #define ATTR_FLAG_PERTHREADFS		0x0080
+#define ATTR_FLAG_PERTHREADIDS		0x0100
 
+/* These flags are not copied from the thread attribute at
+   pthread_create time.  */
+#define ATTR_FLAGS_IGNORED_ATTR \
+  (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)
+
+/* These flags are inherited from the current thread during
+   pthread_create even if they are not specified in the thread
+   attribute.  */
+#define ATTR_FLAGS_INHERITED \
+  (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET | ATTR_FLAG_PERTHREADIDS)
 
 /* Mutex attribute data structure.  */
 struct pthread_mutexattr
diff --git a/sysdeps/nptl/pthread.h b/sysdeps/nptl/pthread.h
index 692d694bbd..ac65069976 100644
--- a/sysdeps/nptl/pthread.h
+++ b/sysdeps/nptl/pthread.h
@@ -418,6 +418,23 @@ void pthread_attr_setperthreadfs_np (pthread_attr_t *__attr, int __enabled)
 int pthread_attr_getperthreadfs_np (const pthread_attr_t *__attr)
   __THROW __nonnull ((1));
 
+/* Control the flag in ATTR whether the thread has its own user and
+   group IDs.  By default, when the real, effective, or saved user or
+   group ID is changed by a thread, this affects the entire process.
+   If a thread is created with this flag set to true, then changing
+   the IDs within that thread will only affect that thread, and user
+   and group ID changes in other threads (whether they have enabled
+   this flag or not) do not affect it.  If a thread has been created
+   with this flag, threads created by it will also have their own,
+   private user and group IDs.  */
+void pthread_attr_setperthreadids_np (pthread_attr_t *__attr, int __enabled)
+  __THROW __nonnull ((1));
+
+/* Return 1 if ATTR enables per-thread user and group IDs, or 0 if
+   not.  See pthread_attr_setperthreadids_np.  */
+int pthread_attr_getperthreadids_np (const pthread_attr_t *__attr)
+  __THROW __nonnull ((1));
+
 /* Get the default attributes used by pthread_create in this process.  */
 extern int pthread_getattr_default_np (pthread_attr_t *__attr)
      __THROW __nonnull ((1));
diff --git a/sysdeps/nptl/setxid.h b/sysdeps/nptl/setxid.h
index de39efc723..09af829d3f 100644
--- a/sysdeps/nptl/setxid.h
+++ b/sysdeps/nptl/setxid.h
@@ -32,7 +32,8 @@
 # define INLINE_SETXID_SYSCALL(name, nr, args...) \
   ({									\
     int __result;							\
-    if (__builtin_expect (__libc_pthread_functions_init, 0))		\
+    if (__libc_pthread_functions_init					\
+	&& !nptl_current_thread_has_separate_ids ())			\
       {									\
 	struct xid_command __cmd;					\
 	__cmd.syscall_no = __NR_##name;					\
@@ -48,7 +49,8 @@
   ({									\
     extern __typeof (__nptl_setxid) __nptl_setxid __attribute__((weak));\
     int __result;							\
-    if (__glibc_unlikely (__nptl_setxid	!= NULL))			      \
+    if (__nptl_setxid != NULL						\
+	&& !nptl_current_thread_has_separate_ids ())			\
       {									\
 	struct xid_command __cmd;					\
 	__cmd.syscall_no = __NR_##name;					\
