diff --git a/libc/bionic/pthread_barrier.cpp b/libc/bionic/pthread_barrier.cpp
new file mode 100644
index 0000000..3227daf
--- /dev/null
+++ b/libc/bionic/pthread_barrier.cpp
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2015 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 <stdatomic.h>
+#include <stdint.h>
+
+#include "private/bionic_futex.h"
+
+int pthread_barrierattr_init(pthread_barrierattr_t* attr) {
+  *attr = 0;
+  return 0;
+}
+
+int pthread_barrierattr_destroy(pthread_barrierattr_t* attr) {
+  *attr = 0;
+  return 0;
+}
+
+int pthread_barrierattr_getpshared(pthread_barrierattr_t* attr, int* pshared) {
+  *pshared = (*attr & 1) ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
+  return 0;
+}
+
+int pthread_barrierattr_setpshared(pthread_barrierattr_t* attr, int pshared) {
+  if (pshared == PTHREAD_PROCESS_SHARED) {
+    *attr |= 1;
+  } else {
+    *attr &= ~1;
+  }
+  return 0;
+}
+
+enum BarrierState {
+  WAIT,
+  RELEASE,
+};
+
+struct pthread_barrier_internal_t {
+  // One barrier can be used for unlimited number of cycles. In each cycle, [init_count]
+  // threads must call pthread_barrier_wait() before any of them successfully return from
+  // the call. It is undefined behavior if there are more than [init_count] threads call
+  // pthread_barrier_wait() in one cycle.
+  uint32_t init_count;
+  // Barrier state. It is WAIT if waiting for more threads to enter the barrier in this cycle,
+  // otherwise threads are leaving the barrier.
+  _Atomic(BarrierState) state;
+  // Number of threads having entered but not left the barrier in this cycle.
+  atomic_uint wait_count;
+  // Whether the barrier is shared across processes.
+  bool pshared;
+  uint32_t __reserved[4];
+};
+
+static_assert(sizeof(pthread_barrier_t) == sizeof(pthread_barrier_internal_t),
+              "pthread_barrier_t should actually be pthread_barrier_internal_t in implementation."
+              );
+
+static_assert(alignof(pthread_barrier_t) >= 4,
+              "pthread_barrier_t should fulfill the alignment of pthread_barrier_internal_t.");
+
+static inline pthread_barrier_internal_t* __get_internal_barrier(pthread_barrier_t* barrier) {
+  return reinterpret_cast<pthread_barrier_internal_t*>(barrier);
+}
+
+int pthread_barrier_init(pthread_barrier_t* barrier_interface, const pthread_barrierattr_t* attr,
+                         unsigned count) {
+  pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
+  if (count == 0) {
+    return EINVAL;
+  }
+  barrier->init_count = count;
+  atomic_init(&barrier->state, WAIT);
+  atomic_init(&barrier->wait_count, 0);
+  barrier->pshared = false;
+  if (attr != nullptr && (*attr & 1)) {
+    barrier->pshared = true;
+  }
+  return 0;
+}
+
+// According to POSIX standard, pthread_barrier_wait() synchronizes memory between participating
+// threads. It means all memory operations made by participating threads before calling
+// pthread_barrier_wait() can be seen by all participating threads after the function call.
+// We establish this by making a happens-before relation between all threads entering the barrier
+// with the last thread entering the barrier, and a happens-before relation between the last
+// thread entering the barrier with all threads leaving the barrier.
+int pthread_barrier_wait(pthread_barrier_t* barrier_interface) {
+  pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
+
+  // Wait until all threads for the previous cycle have left the barrier. This is needed
+  // as a participating thread can call pthread_barrier_wait() again before other
+  // threads have left the barrier. Use acquire operation here to synchronize with
+  // the last thread leaving the previous cycle, so we can read correct wait_count below.
+  while(atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
+    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
+  }
+
+  uint32_t prev_wait_count = atomic_load_explicit(&barrier->wait_count, memory_order_relaxed);
+  while (true) {
+    // It happens when there are more than [init_count] threads trying to enter the barrier
+    // at one cycle. We read the POSIX standard as disallowing this, since additional arriving
+    // threads are not synchronized with respect to the barrier reset. We also don't know of
+    // any reasonable cases in which this would be intentional.
+    if (prev_wait_count >= barrier->init_count) {
+      return EINVAL;
+    }
+    // Use memory_order_acq_rel operation here to synchronize between all threads entering
+    // the barrier with the last thread entering the barrier.
+    if (atomic_compare_exchange_weak_explicit(&barrier->wait_count, &prev_wait_count,
+                                              prev_wait_count + 1u, memory_order_acq_rel,
+                                              memory_order_relaxed)) {
+      break;
+    }
+  }
+
+  int result = 0;
+  if (prev_wait_count + 1 == barrier->init_count) {
+    result = PTHREAD_BARRIER_SERIAL_THREAD;
+    if (prev_wait_count != 0) {
+      // Use release operation here to synchronize between the last thread entering the
+      // barrier with all threads leaving the barrier.
+      atomic_store_explicit(&barrier->state, RELEASE, memory_order_release);
+      __futex_wake_ex(&barrier->state, barrier->pshared, prev_wait_count);
+    }
+  } else {
+    // Use acquire operation here to synchronize between the last thread entering the
+    // barrier with all threads leaving the barrier.
+    while (atomic_load_explicit(&barrier->state, memory_order_acquire) == WAIT) {
+      __futex_wait_ex(&barrier->state, barrier->pshared, WAIT, nullptr);
+    }
+  }
+  // Use release operation here to make it not reordered with previous operations.
+  if (atomic_fetch_sub_explicit(&barrier->wait_count, 1, memory_order_release) == 1) {
+    // Use release operation here to synchronize with threads entering the barrier for
+    // the next cycle, or the thread calling pthread_barrier_destroy().
+    atomic_store_explicit(&barrier->state, WAIT, memory_order_release);
+    __futex_wake_ex(&barrier->state, barrier->pshared, barrier->init_count);
+  }
+  return result;
+}
+
+int pthread_barrier_destroy(pthread_barrier_t* barrier_interface) {
+  pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
+  if (barrier->init_count == 0) {
+    return EINVAL;
+  }
+  // Use acquire operation here to synchronize with the last thread leaving the barrier.
+  // So we can read correct wait_count below.
+  while (atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
+    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
+  }
+  if (atomic_load_explicit(&barrier->wait_count, memory_order_relaxed) != 0) {
+    return EBUSY;
+  }
+  barrier->init_count = 0;
+  return 0;
+}