diff --git a/docs/mte.md b/docs/mte.md
index d496b29..3034cc7 100644
--- a/docs/mte.md
+++ b/docs/mte.md
@@ -168,7 +168,7 @@
 The bootloader API allows userspace to enable MTE on devices that do not ship
 with MTE enabled by default.
 
-See [SAC bootloader support] for the API definition. In AOSP, this API is
+See [SAC MTE bootloader support] for the API definition. In AOSP, this API is
 implemented in [system/extras/mtectrl]. mtectrl.rc handles the property
 changes and invokes mtectrl to update the misc partition to communicate
 with the bootloader.
diff --git a/docs/status.md b/docs/status.md
index 94784de..e7111d9 100644
--- a/docs/status.md
+++ b/docs/status.md
@@ -62,6 +62,7 @@
 New libc functions in API level 36:
   * `qsort_r`, `sig2str`/`str2sig` (POSIX Issue 8 additions).
   * GNU/BSD extension `lchmod`.
+  * GNU extensions `pthread_getaffinity_np`/`pthread_setaffinity_np`.
   * New system call wrapper: `mseal` (`<sys/mman.h>`).
 
 New libc functions in V (API level 35):
diff --git a/libc/Android.bp b/libc/Android.bp
index 5ae8c4f..e0d8994 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -941,6 +941,7 @@
         "bionic/pthread_detach.cpp",
         "bionic/pthread_equal.cpp",
         "bionic/pthread_exit.cpp",
+        "bionic/pthread_getaffinity.cpp",
         "bionic/pthread_getcpuclockid.cpp",
         "bionic/pthread_getschedparam.cpp",
         "bionic/pthread_gettid_np.cpp",
@@ -954,6 +955,7 @@
         "bionic/pthread_sigqueue.cpp",
         "bionic/pthread_self.cpp",
         "bionic/pthread_setname_np.cpp",
+        "bionic/pthread_setaffinity.cpp",
         "bionic/pthread_setschedparam.cpp",
         "bionic/pthread_spinlock.cpp",
         "bionic/ptrace.cpp",
diff --git a/libc/bionic/pthread_getaffinity.cpp b/libc/bionic/pthread_getaffinity.cpp
new file mode 100644
index 0000000..9ce436c
--- /dev/null
+++ b/libc/bionic/pthread_getaffinity.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <errno.h>
+
+#include "private/ErrnoRestorer.h"
+#include "pthread_internal.h"
+
+int pthread_getaffinity_np(pthread_t t, size_t cpu_set_size, cpu_set_t* cpu_set) {
+  ErrnoRestorer errno_restorer;
+
+  pid_t tid = __pthread_internal_gettid(t, "pthread_getaffinity_np");
+  if (tid == -1) return ESRCH;
+
+  if (sched_getaffinity(tid, cpu_set_size, cpu_set) == -1) return errno;
+  return 0;
+}
diff --git a/libc/bionic/pthread_setaffinity.cpp b/libc/bionic/pthread_setaffinity.cpp
new file mode 100644
index 0000000..6db418e
--- /dev/null
+++ b/libc/bionic/pthread_setaffinity.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <errno.h>
+
+#include "private/ErrnoRestorer.h"
+#include "pthread_internal.h"
+
+int pthread_setaffinity_np(pthread_t t, size_t cpu_set_size, const cpu_set_t* cpu_set) {
+  ErrnoRestorer errno_restorer;
+
+  pid_t tid = __pthread_internal_gettid(t, "pthread_setaffinity_np");
+  if (tid == -1) return ESRCH;
+
+  if (sched_setaffinity(tid, cpu_set_size, cpu_set) == -1) return errno;
+  return 0;
+}
diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index 8b78a74..cdf1b8c 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -314,17 +314,60 @@
 
 pthread_t pthread_self(void) __attribute_const__;
 
-#if defined(__USE_GNU)
-
-#if __BIONIC_AVAILABILITY_GUARD(26)
+#if defined(__USE_GNU) && __BIONIC_AVAILABILITY_GUARD(26)
+/**
+ * [pthread_getname_np(3)](https://man7.org/linux/man-pages/man3/pthread_getname_np.3.html)
+ * gets the name of the given thread.
+ * Names are at most 16 bytes (including '\0').
+ *
+ * Returns 0 on success and returns an error number on failure.
+ *
+ * Available since API level 26.
+ */
 int pthread_getname_np(pthread_t __pthread, char* _Nonnull __buf, size_t __n) __INTRODUCED_IN(26);
-#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
-
 #endif
-/* TODO: this should be __USE_GNU too. */
+
+/**
+ * [pthread_setname_np(3)](https://man7.org/linux/man-pages/man3/pthread_setname_np.3.html)
+ * sets the name of the given thread.
+ * Names are at most 16 bytes (including '\0').
+ * Truncation must be done by the caller;
+ * calls with longer names will fail with ERANGE.
+ *
+ * Returns 0 on success and returns an error number on failure.
+ *
+ * This should only have been available under _GNU_SOURCE,
+ * but is always available on Android by historical accident.
+ */
 int pthread_setname_np(pthread_t __pthread, const char* _Nonnull __name);
 
 /**
+ * [pthread_getaffinity_np(3)](https://man7.org/linux/man-pages/man3/pthread_getaffinity_np.3.html)
+ * gets the CPU affinity mask for the given thread.
+ *
+ * Returns 0 on success and returns an error number on failure.
+ *
+ * Available since API level 36.
+ * See sched_getaffinity() and pthread_gettid_np() for greater portability.
+ */
+#if defined(__USE_GNU) && __BIONIC_AVAILABILITY_GUARD(36)
+int pthread_getaffinity_np(pthread_t __pthread, size_t __cpu_set_size, cpu_set_t* __cpu_set) __INTRODUCED_IN(36);
+#endif
+
+/**
+ * [pthread_setaffinity_np(3)](https://man7.org/linux/man-pages/man3/pthread_setaffinity_np.3.html)
+ * sets the CPU affinity mask for the given thread.
+ *
+ * Returns 0 on success and returns an error number on failure.
+ *
+ * Available since API level 36.
+ * See sched_getaffinity() and pthread_gettid_np() for greater portability.
+ */
+#if defined(__USE_GNU) && __BIONIC_AVAILABILITY_GUARD(36)
+int pthread_setaffinity_np(pthread_t __pthread, size_t __cpu_set_size, const cpu_set_t* __cpu_set) __INTRODUCED_IN(36);
+#endif
+
+/**
  * [pthread_setschedparam(3)](https://man7.org/linux/man-pages/man3/pthread_setschedparam.3.html)
  * sets the scheduler policy and parameters of the given thread.
  *
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index d8636a2..86dcc39 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1612,6 +1612,8 @@
   global:
     lchmod;
     mseal;
+    pthread_getaffinity_np;
+    pthread_setaffinity_np;
     qsort_r;
     sig2str;
     str2sig;
diff --git a/tests/grp_pwd_test.cpp b/tests/grp_pwd_test.cpp
index 7b7e0e5..3f93c8a 100644
--- a/tests/grp_pwd_test.cpp
+++ b/tests/grp_pwd_test.cpp
@@ -480,6 +480,18 @@
       EXPECT_STREQ(getpwuid(AID_CROS_EC)->pw_name, "cros_ec");
     }
   }
+  // AID_MMD (1095) was added in API level 36, but "trunk stable" means
+  // that the 2024Q* builds are tested with the _previous_ release's CTS.
+  if (android::base::GetIntProperty("ro.build.version.sdk", 0) == 35) {
+#if !defined(AID_MMD)
+#define AID_MMD 1095
+#endif
+    ids.erase(AID_MMD);
+    expected_ids.erase(AID_MMD);
+    if (getpwuid(AID_MMD)) {
+      EXPECT_STREQ(getpwuid(AID_MMD)->pw_name, "mmd");
+    }
+  }
 
   EXPECT_EQ(expected_ids, ids) << return_differences();
 }
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 7223784..1421365 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -3137,3 +3137,23 @@
   GTEST_SKIP() << "bionic-only test";
 #endif
 }
+
+TEST(pthread, pthread_getaffinity_np_failure) {
+  // Trivial test of the errno-preserving/returning behavior.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
+  errno = 0;
+  ASSERT_EQ(EINVAL, pthread_getaffinity_np(pthread_self(), 0, nullptr));
+  ASSERT_ERRNO(0);
+#pragma clang diagnostic pop
+}
+
+TEST(pthread, pthread_setaffinity_np_failure) {
+  // Trivial test of the errno-preserving/returning behavior.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
+  errno = 0;
+  ASSERT_EQ(EINVAL, pthread_setaffinity_np(pthread_self(), 0, nullptr));
+  ASSERT_ERRNO(0);
+#pragma clang diagnostic pop
+}
diff --git a/tests/sched_test.cpp b/tests/sched_test.cpp
index 0231de4..396d3b7 100644
--- a/tests/sched_test.cpp
+++ b/tests/sched_test.cpp
@@ -305,8 +305,19 @@
 }
 
 TEST(sched, sched_getaffinity_failure) {
+  // Trivial test of the errno-preserving/returning behavior.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wnonnull"
   ASSERT_EQ(-1, sched_getaffinity(getpid(), 0, nullptr));
+  ASSERT_ERRNO(EINVAL);
+#pragma clang diagnostic pop
+}
+
+TEST(sched, sched_setaffinity_failure) {
+  // Trivial test of the errno-preserving/returning behavior.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
+  ASSERT_EQ(-1, sched_setaffinity(getpid(), 0, nullptr));
+  ASSERT_ERRNO(EINVAL);
 #pragma clang diagnostic pop
 }