diff --git a/libc/bionic/pthread_internal.cpp b/libc/bionic/pthread_internal.cpp
new file mode 100644
index 0000000..8946f79
--- /dev/null
+++ b/libc/bionic/pthread_internal.cpp
@@ -0,0 +1,98 @@
+/*
+ * 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_internal.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include "private/bionic_futex.h"
+#include "private/bionic_tls.h"
+#include "private/libc_logging.h"
+#include "private/ScopedPthreadMutexLocker.h"
+
+static pthread_internal_t* g_thread_list = NULL;
+static pthread_mutex_t g_thread_list_lock = PTHREAD_MUTEX_INITIALIZER;
+
+pthread_t __pthread_internal_add(pthread_internal_t* thread) {
+  ScopedPthreadMutexLocker locker(&g_thread_list_lock);
+
+  // We insert at the head.
+  thread->next = g_thread_list;
+  thread->prev = NULL;
+  if (thread->next != NULL) {
+    thread->next->prev = thread;
+  }
+  g_thread_list = thread;
+  return reinterpret_cast<pthread_t>(thread);
+}
+
+void __pthread_internal_remove(pthread_internal_t* thread) {
+  ScopedPthreadMutexLocker locker(&g_thread_list_lock);
+
+  if (thread->next != NULL) {
+    thread->next->prev = thread->prev;
+  }
+  if (thread->prev != NULL) {
+    thread->prev->next = thread->next;
+  } else {
+    g_thread_list = thread->next;
+  }
+}
+
+static void __pthread_internal_free(pthread_internal_t* thread) {
+  if (thread->mmap_size != 0) {
+    // Free mapped space, including thread stack and pthread_internal_t.
+    munmap(thread->attr.stack_base, thread->mmap_size);
+  }
+}
+
+void __pthread_internal_remove_and_free(pthread_internal_t* thread) {
+  __pthread_internal_remove(thread);
+  __pthread_internal_free(thread);
+}
+
+pthread_internal_t* __pthread_internal_find(pthread_t thread_id) {
+  pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(thread_id);
+
+  // check if thread is pthread_self() before acquiring the lock
+  if (thread == __get_thread()) {
+    return thread;
+  }
+
+  ScopedPthreadMutexLocker locker(&g_thread_list_lock);
+
+  for (pthread_internal_t* t = g_thread_list; t != NULL; t = t->next) {
+    if (t == thread) {
+      return thread;
+    }
+  }
+  return NULL;
+}