diff --git a/libc/src/pthread/pthread_spin_init.h b/libc/src/pthread/pthread_spin_init.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for pthread_spin_init function ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_INIT_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_INIT_H
+
+#include "src/__support/macros/config.h"
+#include <pthread.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_spin_init(pthread_spinlock_t *lock, int pshared);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_INIT_H
diff --git a/libc/src/pthread/pthread_spin_lock.cpp b/libc/src/pthread/pthread_spin_lock.cpp
@@ -0,0 +1,47 @@
+//===-- Implementation of pthread_spin_lock function ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_spin_lock.h"
+#include "hdr/errno_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/threads/identifier.h"
+#include "src/__support/threads/spin_lock.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_spinlock_t::__lockword) == sizeof(SpinLock) &&
+                  alignof(decltype(pthread_spinlock_t::__lockword)) ==
+                      alignof(SpinLock),
+              "pthread_spinlock_t::__lockword and SpinLock must be of the same "
+              "size and alignment");
+
+LLVM_LIBC_FUNCTION(int, pthread_spin_lock, (pthread_spinlock_t * lock)) {
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_lock() or pthread_spin_trylock() does not refer to an
+  // initialized spin lock object, it is recommended that the function should
+  // fail and report an [EINVAL] error.
+  if (!lock)
+    return EINVAL;
+  auto spin_lock = reinterpret_cast<SpinLock *>(&lock->__lockword);
+  if (spin_lock->is_invalid())
+    return EINVAL;
+
+  pid_t self_tid = internal::gettid();
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_lock() refers to a spin lock object for which the calling
+  // thread already holds the lock, it is recommended that the function should
+  // fail and report an [EDEADLK] error.
+  if (lock->__owner == self_tid)
+    return EDEADLK;
+
+  spin_lock->lock();
+  lock->__owner = self_tid;
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/pthread_spin_lock.h b/libc/src/pthread/pthread_spin_lock.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for pthread_spin_lock function ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_LOCK_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_LOCK_H
+
+#include "src/__support/macros/config.h"
+#include <pthread.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_spin_lock(pthread_spinlock_t *lock);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_LOCK_H
diff --git a/libc/src/pthread/pthread_spin_trylock.cpp b/libc/src/pthread/pthread_spin_trylock.cpp
@@ -0,0 +1,41 @@
+//===-- Implementation of pthread_spin_trylock function -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_spin_trylock.h"
+#include "hdr/errno_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/threads/identifier.h"
+#include "src/__support/threads/spin_lock.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_spinlock_t::__lockword) == sizeof(SpinLock) &&
+                  alignof(decltype(pthread_spinlock_t::__lockword)) ==
+                      alignof(SpinLock),
+              "pthread_spinlock_t::__lockword and SpinLock must be of the same "
+              "size and alignment");
+
+LLVM_LIBC_FUNCTION(int, pthread_spin_trylock, (pthread_spinlock_t * lock)) {
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_lock() or pthread_spin_trylock() does not refer to an
+  // initialized spin lock object, it is recommended that the function should
+  // fail and report an [EINVAL] error.
+  if (!lock)
+    return EINVAL;
+  auto spin_lock = reinterpret_cast<SpinLock *>(&lock->__lockword);
+  if (!spin_lock || spin_lock->is_invalid())
+    return EINVAL;
+  // Try to acquire the lock without blocking.
+  if (!spin_lock->try_lock())
+    return EBUSY;
+  // We have acquired the lock. Update the owner field.
+  lock->__owner = internal::gettid();
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/pthread_spin_trylock.h b/libc/src/pthread/pthread_spin_trylock.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for pthread_spin_trylock function ---*- C++
+//-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_TRYLOCK_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_TRYLOCK_H
+
+#include "src/__support/macros/config.h"
+#include <pthread.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_spin_trylock(pthread_spinlock_t *lock);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_TRYLOCK_H
diff --git a/libc/src/pthread/pthread_spin_unlock.cpp b/libc/src/pthread/pthread_spin_unlock.cpp
@@ -0,0 +1,44 @@
+//===-- Implementation of pthread_spin_unlock function --------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_spin_unlock.h"
+#include "hdr/errno_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/threads/identifier.h"
+#include "src/__support/threads/spin_lock.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_spinlock_t::__lockword) == sizeof(SpinLock) &&
+                  alignof(decltype(pthread_spinlock_t::__lockword)) ==
+                      alignof(SpinLock),
+              "pthread_spinlock_t::__lockword and SpinLock must be of the same "
+              "size and alignment");
+
+LLVM_LIBC_FUNCTION(int, pthread_spin_unlock, (pthread_spinlock_t * lock)) {
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_lock() or pthread_spin_trylock() does not refer to an
+  // initialized spin lock object, it is recommended that the function should
+  // fail and report an [EINVAL] error.
+  if (!lock)
+    return EINVAL;
+  auto spin_lock = reinterpret_cast<SpinLock *>(&lock->__lockword);
+  if (!spin_lock || spin_lock->is_invalid())
+    return EINVAL;
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_unlock() refers to a spin lock object for which the current
+  // thread does not hold the lock, it is recommended that the function should
+  // fail and report an [EPERM] error.
+  if (lock->__owner != internal::gettid())
+    return EPERM;
+  // Release the lock.
+  lock->__owner = 0;
+  spin_lock->unlock();
+  return 0;
+}
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/pthread_spin_unlock.h b/libc/src/pthread/pthread_spin_unlock.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for pthread_spin_unlock function ---*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_UNLOCK_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_UNLOCK_H
+
+#include "src/__support/macros/config.h"
+#include <pthread.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_spin_unlock(pthread_spinlock_t *lock);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SPIN_UNLOCK_H
diff --git a/libc/test/integration/src/pthread/CMakeLists.txt b/libc/test/integration/src/pthread/CMakeLists.txt
@@ -24,9 +24,9 @@ add_integration_test(
   SRCS
     pthread_rwlock_test.cpp
   DEPENDS
+    libc.hdr.time_macros
+    libc.hdr.errno_macros
     libc.include.pthread
-    libc.include.time
-    libc.include.errno
     libc.src.pthread.pthread_rwlock_destroy
     libc.src.pthread.pthread_rwlock_init
     libc.src.pthread.pthread_rwlock_rdlock
@@ -59,6 +59,24 @@ add_integration_test(
     libc.src.__support.threads.sleep
 )
 
+add_integration_test(
+  pthread_spinlock_test
+  SUITE
+    libc-pthread-integration-tests
+  SRCS
+    pthread_spinlock_test.cpp
+  DEPENDS
+    libc.hdr.errno_macros
+    libc.include.pthread
+    libc.src.pthread.pthread_spin_init
+    libc.src.pthread.pthread_spin_destroy
+    libc.src.pthread.pthread_spin_lock
+    libc.src.pthread.pthread_spin_trylock
+    libc.src.pthread.pthread_spin_unlock
+    libc.src.pthread.pthread_create
+    libc.src.pthread.pthread_join
+)
+
 add_integration_test(
   pthread_test
   SUITE

diff --git a/libc/test/integration/src/pthread/pthread_rwlock_test.cpp b/libc/test/integration/src/pthread/pthread_rwlock_test.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "hdr/errno_macros.h"
+#include "hdr/time_macros.h"
 #include "src/__support/CPP/atomic.h"
 #include "src/__support/CPP/new.h"
 #include "src/__support/OSUtil/syscall.h"
@@ -40,9 +42,7 @@
 #include "src/time/clock_gettime.h"
 #include "src/unistd/fork.h"
 #include "test/IntegrationTest/test.h"
-#include <errno.h>
 #include <pthread.h>
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 namespace rwlock {

diff --git a/libc/test/integration/src/pthread/pthread_spinlock_test.cpp b/libc/test/integration/src/pthread/pthread_spinlock_test.cpp
@@ -0,0 +1,145 @@
+//===-- Tests for pthread_spinlock ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "hdr/errno_macros.h"
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_join.h"
+#include "src/pthread/pthread_spin_destroy.h"
+#include "src/pthread/pthread_spin_init.h"
+#include "src/pthread/pthread_spin_lock.h"
+#include "src/pthread/pthread_spin_trylock.h"
+#include "src/pthread/pthread_spin_unlock.h"
+#include "test/IntegrationTest/test.h"
+#include <pthread.h>
+
+namespace {
+void smoke_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+}
+
+void trylock_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_trylock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_trylock(&lock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_trylock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+}
+
+void destroy_held_lock_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+}
+
+void use_after_destroy_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&lock), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_trylock(&lock), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), EINVAL);
+}
+
+void unlock_without_holding_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), EPERM);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+}
+
+void deadlock_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&lock), EDEADLK);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&lock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+}
+
+void null_lock_test() {
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(nullptr, 0), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_trylock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(nullptr), EINVAL);
+}
+
+void pshared_attribute_test() {
+  pthread_spinlock_t lock;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_SHARED),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE),
+            0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&lock), 0);
+
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&lock, -1), EINVAL);
+}
+
+void multi_thread_test() {
+  struct shared_data {
+    pthread_spinlock_t lock;
+    int count = 0;
+  } shared;
+  pthread_t thread[10];
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_init(&shared.lock, 0), 0);
+  for (int i = 0; i < 10; ++i) {
+    ASSERT_EQ(
+        LIBC_NAMESPACE::pthread_create(
+            &thread[i], nullptr,
+            [](void *arg) -> void * {
+              auto *data = static_cast<shared_data *>(arg);
+              for (int j = 0; j < 1000; ++j) {
+                ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_lock(&data->lock), 0);
+                data->count += j;
+                ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_unlock(&data->lock), 0);
+              }
+              return nullptr;
+            },
+            &shared),
+        0);
+  }
+  for (int i = 0; i < 10; ++i) {
+    ASSERT_EQ(LIBC_NAMESPACE::pthread_join(thread[i], nullptr), 0);
+  }
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_spin_destroy(&shared.lock), 0);
+  ASSERT_EQ(shared.count, 1000 * 999 * 5);
+}
+
+} // namespace
+
+TEST_MAIN() {
+  smoke_test();
+  trylock_test();
+  destroy_held_lock_test();
+  use_after_destroy_test();
+  unlock_without_holding_test();
+  deadlock_test();
+  multi_thread_test();
+  null_lock_test();
+  pshared_attribute_test();
+  return 0;
+}