diff --git a/libc/bionic/pthread_exit.cpp b/libc/bionic/pthread_exit.cpp
new file mode 100644
index 0000000..aa9bd38
--- /dev/null
+++ b/libc/bionic/pthread_exit.cpp
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2008 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 <pthread.h>
+
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include "pthread_internal.h"
+
+extern "C" void _exit_with_stack_teardown(void*, size_t, int);
+extern "C" void __exit(int);
+
+/* CAVEAT: our implementation of pthread_cleanup_push/pop doesn't support C++ exceptions
+ *         and thread cancelation
+ */
+
+void __pthread_cleanup_push(__pthread_cleanup_t* c, __pthread_cleanup_func_t routine, void* arg) {
+  pthread_internal_t* thread = __get_thread();
+  c->__cleanup_routine = routine;
+  c->__cleanup_arg = arg;
+  c->__cleanup_prev = thread->cleanup_stack;
+  thread->cleanup_stack = c;
+}
+
+void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) {
+  pthread_internal_t* thread = __get_thread();
+  thread->cleanup_stack = c->__cleanup_prev;
+  if (execute) {
+    c->__cleanup_routine(c->__cleanup_arg);
+  }
+}
+
+void pthread_exit(void* retval) {
+  pthread_internal_t* thread = __get_thread();
+
+  // Call the cleanup handlers first.
+  while (thread->cleanup_stack) {
+    __pthread_cleanup_t* c = thread->cleanup_stack;
+    thread->cleanup_stack = c->__cleanup_prev;
+    c->__cleanup_routine(c->__cleanup_arg);
+  }
+
+  // Call the TLS destructors. It is important to do that before removing this
+  // thread from the global list. This will ensure that if someone else deletes
+  // a TLS key, the corresponding value will be set to NULL in this thread's TLS
+  // space (see pthread_key_delete).
+  pthread_key_clean_all();
+
+  if (thread->alternate_signal_stack != NULL) {
+    // Tell the kernel to stop using the alternate signal stack.
+    stack_t ss;
+    ss.ss_sp = NULL;
+    ss.ss_flags = SS_DISABLE;
+    sigaltstack(&ss, NULL);
+
+    // Free it.
+    munmap(thread->alternate_signal_stack, SIGSTKSZ);
+    thread->alternate_signal_stack = NULL;
+  }
+
+  // Keep track of what we need to know about the stack before we lose the pthread_internal_t.
+  void* stack_base = thread->attr.stack_base;
+  size_t stack_size = thread->attr.stack_size;
+  bool user_allocated_stack = ((thread->attr.flags & PTHREAD_ATTR_FLAG_USER_ALLOCATED_STACK) != 0);
+
+  // If the thread is detached, destroy the pthread_internal_t,
+  // otherwise keep it in memory and signal any joiners.
+  pthread_mutex_lock(&gThreadListLock);
+  if (thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) {
+    _pthread_internal_remove_locked(thread);
+  } else {
+    // Make sure that the pthread_internal_t doesn't have stale pointers to a stack that
+    // will be unmapped after the exit call below.
+    if (!user_allocated_stack) {
+      thread->attr.stack_base = NULL;
+      thread->attr.stack_size = 0;
+      thread->tls = NULL;
+    }
+
+    // Indicate that the thread has exited for joining threads.
+    thread->attr.flags |= PTHREAD_ATTR_FLAG_ZOMBIE;
+    thread->return_value = retval;
+
+    // Signal the joining thread if present.
+    if (thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) {
+      pthread_cond_signal(&thread->join_cond);
+    }
+  }
+  pthread_mutex_unlock(&gThreadListLock);
+
+  if (user_allocated_stack) {
+    // Cleaning up this thread's stack is the creator's responsibility, not ours.
+    __exit(0);
+  } else {
+    // We need to munmap the stack we're running on before calling exit.
+    // That's not something we can do in C.
+
+    // We don't want to take a signal after we've unmapped the stack.
+    // That's one last thing we can handle in C.
+    sigset_t mask;
+    sigfillset(&mask);
+    sigprocmask(SIG_SETMASK, &mask, NULL);
+
+    _exit_with_stack_teardown(stack_base, stack_size, 0);
+  }
+
+  /* NOTREACHED, but we told the compiler this function is noreturn, and it doesn't believe us. */
+  abort();
+}