diff --git a/libc/src/spawn/posix_spawn_file_actions_addopen.cpp b/libc/src/spawn/posix_spawn_file_actions_addopen.cpp
@@ -0,0 +1,43 @@
+//===-- Implementation of posix_spawn_file_actions_addopen ----------------===//
+//
+// 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 "posix_spawn_file_actions_addopen.h"
+
+#include "file_actions.h"
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <spawn.h>
+#include <stdlib.h> // For malloc
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, posix_spawn_file_actions_addopen,
+                   (posix_spawn_file_actions_t *__restrict actions, int fd,
+                    const char *__restrict path, int oflag, mode_t mode)) {
+  if (actions == nullptr)
+    return EINVAL;
+  if (fd < 0)
+    return EBADF;
+
+  auto *act = reinterpret_cast<SpawnFileOpenAction *>(
+      malloc(sizeof(SpawnFileOpenAction)));
+  if (act == nullptr)
+    return ENOMEM;
+
+  act->type = BaseSpawnFileAction::OPEN;
+  act->fd = fd;
+  act->path = path;
+  act->oflag = oflag;
+  act->mode = mode;
+  act->next = nullptr;
+  enque_spawn_action(actions, act);
+  return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/spawn/posix_spawn_file_actions_addopen.h b/libc/src/spawn/posix_spawn_file_actions_addopen.h
@@ -0,0 +1,22 @@
+//===-- Impl header for posix_spawn_file_actions_addopen --------*- 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_SPAWN_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN_H
+#define LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN_H
+
+#include <spawn.h>
+
+namespace __llvm_libc {
+
+int posix_spawn_file_actions_addopen(
+    posix_spawn_file_actions_t *__restrict actions, int fd,
+    const char *__restrict path, int oflag, mode_t mode);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN_H
diff --git a/libc/src/spawn/posix_spawn_file_actions_destroy.cpp b/libc/src/spawn/posix_spawn_file_actions_destroy.cpp
@@ -0,0 +1,40 @@
+//===-- Implementation of posix_spawn_file_actions_destroy ----------------===//
+//
+// 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 "posix_spawn_file_actions_destroy.h"
+
+#include "file_actions.h"
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <spawn.h>
+#include <stdlib.h> // For free
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, posix_spawn_file_actions_destroy,
+                   (posix_spawn_file_actions_t * actions)) {
+  if (actions == nullptr)
+    return EINVAL;
+  if (actions->__front == nullptr)
+    return 0;
+
+  auto *act = reinterpret_cast<BaseSpawnFileAction *>(actions->__front);
+  actions->__front = nullptr;
+  actions->__back = nullptr;
+
+  while (act != nullptr) {
+    auto *next = act->next;
+    free(act);
+    act = next;
+  }
+
+  return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/spawn/posix_spawn_file_actions_destroy.h b/libc/src/spawn/posix_spawn_file_actions_destroy.h
@@ -0,0 +1,20 @@
+//===-- Impl header for posix_spawn_file_actions_destroy --------*- 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_SPAWN_POSIX_SPAWN_FILE_ACTIONS_DESTROY_H
+#define LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_DESTROY_H
+
+#include <spawn.h>
+
+namespace __llvm_libc {
+
+int posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *actions);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_DESTROY_H
diff --git a/libc/src/spawn/posix_spawn_file_actions_init.cpp b/libc/src/spawn/posix_spawn_file_actions_init.cpp
@@ -0,0 +1,24 @@
+//===-- Implementation of posix_spawn_file_actions_init -------------------===//
+//
+// 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 "posix_spawn_file_actions_init.h"
+
+#include "src/__support/common.h"
+
+#include <spawn.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, posix_spawn_file_actions_init,
+                   (posix_spawn_file_actions_t * actions)) {
+  actions->__front = nullptr;
+  actions->__back = nullptr;
+  return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/spawn/posix_spawn_file_actions_init.h b/libc/src/spawn/posix_spawn_file_actions_init.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for posix_spawn_file_actions_init -*- 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_SPAWN_POSIX_SPAWN_FILE_ACTIONS_INIT_H
+#define LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_INIT_H
+
+#include <spawn.h>
+
+namespace __llvm_libc {
+
+int posix_spawn_file_actions_init(posix_spawn_file_actions_t *actions);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SPAWN_POSIX_SPAWN_FILE_ACTIONS_INIT_H
diff --git a/libc/test/src/CMakeLists.txt b/libc/test/src/CMakeLists.txt
@@ -52,6 +52,7 @@ add_subdirectory(dirent)
 # since assert uses the signal API, we disable assert also.
 # add_subdirectory(assert)
 add_subdirectory(signal)
+add_subdirectory(spawn)
 add_subdirectory(time)
 
 if(${LIBC_TARGET_OS} STREQUAL "linux")

diff --git a/libc/test/src/spawn/CMakeLists.txt b/libc/test/src/spawn/CMakeLists.txt
@@ -0,0 +1,18 @@
+add_libc_testsuite(libc_spawn_unittests)
+
+add_libc_unittest(
+  posix_spawn_file_actions_test
+  SUITE
+    libc_spawn_unittests
+  SRCS
+    posix_spawn_file_actions_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.spawn
+    libc.src.spawn.file_actions
+    libc.src.spawn.posix_spawn_file_actions_addclose
+    libc.src.spawn.posix_spawn_file_actions_adddup2
+    libc.src.spawn.posix_spawn_file_actions_addopen
+    libc.src.spawn.posix_spawn_file_actions_destroy
+    libc.src.spawn.posix_spawn_file_actions_init
+)
diff --git a/libc/test/src/spawn/posix_spawn_file_actions_test.cpp b/libc/test/src/spawn/posix_spawn_file_actions_test.cpp
@@ -0,0 +1,75 @@
+//===-- Unittests for posix_spwan_file_actions_t manipulation -------------===//
+//
+// 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/spawn/file_actions.h"
+#include "src/spawn/posix_spawn_file_actions_addclose.h"
+#include "src/spawn/posix_spawn_file_actions_adddup2.h"
+#include "src/spawn/posix_spawn_file_actions_addopen.h"
+#include "src/spawn/posix_spawn_file_actions_destroy.h"
+#include "src/spawn/posix_spawn_file_actions_init.h"
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <spawn.h>
+#include <stdint.h>
+
+TEST(LlvmLibcPosixSpawnFileActionsTest, AddActions) {
+  posix_spawn_file_actions_t actions;
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_init(&actions), 0);
+
+  ASSERT_EQ(uintptr_t(actions.__front), uintptr_t(nullptr));
+  ASSERT_EQ(uintptr_t(actions.__back), uintptr_t(nullptr));
+
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_addclose(&actions, 10), 0);
+  ASSERT_NE(uintptr_t(actions.__front), uintptr_t(nullptr));
+  ASSERT_NE(uintptr_t(actions.__back), uintptr_t(nullptr));
+
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_adddup2(&actions, 11, 12), 0);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_addopen(&actions, 13,
+                                                          "path/to/file", 0, 0),
+            0);
+
+  __llvm_libc::BaseSpawnFileAction *act =
+      reinterpret_cast<__llvm_libc::BaseSpawnFileAction *>(actions.__front);
+  int action_count = 0;
+  while (act != nullptr) {
+    ++action_count;
+    if (action_count == 1)
+      ASSERT_EQ(act->type, __llvm_libc::BaseSpawnFileAction::CLOSE);
+    if (action_count == 2)
+      ASSERT_EQ(act->type, __llvm_libc::BaseSpawnFileAction::DUP2);
+    if (action_count == 3)
+      ASSERT_EQ(act->type, __llvm_libc::BaseSpawnFileAction::OPEN);
+    act = act->next;
+  }
+  ASSERT_EQ(action_count, 3);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_destroy(&actions), 0);
+}
+
+TEST(LlvmLibcPosixSpawnFileActionsTest, InvalidActions) {
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_addclose(nullptr, 1), EINVAL);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_adddup2(nullptr, 1, 2),
+            EINVAL);
+  ASSERT_EQ(
+      __llvm_libc::posix_spawn_file_actions_addopen(nullptr, 1, nullptr, 0, 0),
+      EINVAL);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_destroy(nullptr), EINVAL);
+
+  posix_spawn_file_actions_t actions;
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_init(&actions), 0);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_addclose(&actions, -1),
+            EBADF);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_adddup2(&actions, -1, 2),
+            EBADF);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_adddup2(&actions, 1, -2),
+            EBADF);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_addopen(&actions, -1, nullptr,
+                                                          0, 0),
+            EBADF);
+  ASSERT_EQ(__llvm_libc::posix_spawn_file_actions_destroy(&actions), 0);
+}