diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
@@ -1,3 +1,42 @@
+add_entrypoint_object(
+  close
+  SRCS
+    close.cpp
+  HDRS
+    ../close.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.__errno_location
+)
+
+add_entrypoint_object(
+  fsync
+  SRCS
+    fsync.cpp
+  HDRS
+    ../fsync.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.__errno_location
+)
+
+add_entrypoint_object(
+  read
+  SRCS
+    read.cpp
+  HDRS
+    ../read.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.__errno_location
+)
+
 add_entrypoint_object(
   write
   SRCS

diff --git a/libc/src/unistd/linux/close.cpp b/libc/src/unistd/linux/close.cpp
@@ -0,0 +1,28 @@
+//===-- Linux implementation of close -------------------------------------===//
+//
+// 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/unistd/close.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, close, (int fd)) {
+  long ret = __llvm_libc::syscall(SYS_close, fd);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/unistd/linux/fsync.cpp b/libc/src/unistd/linux/fsync.cpp
@@ -0,0 +1,28 @@
+//===-- Linux implementation of fsync -------------------------------------===//
+//
+// 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/unistd/fsync.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, fsync, (int fd)) {
+  long ret = __llvm_libc::syscall(SYS_fsync, fd);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/unistd/linux/read.cpp b/libc/src/unistd/linux/read.cpp
@@ -0,0 +1,28 @@
+//===-- Linux implementation of read --------------------------------------===//
+//
+// 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/unistd/read.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(ssize_t, read, (int fd, void *buf, size_t count)) {
+  long ret = __llvm_libc::syscall(SYS_read, fd, buf, count);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/unistd/linux/write.cpp b/libc/src/unistd/linux/write.cpp
@@ -12,7 +12,7 @@
 #include "src/__support/common.h"
 
 #include <errno.h>
-#include <sys/syscall.h>          // For syscall numbers.
+#include <sys/syscall.h> // For syscall numbers.
 
 namespace __llvm_libc {
 

diff --git a/libc/src/unistd/read.h b/libc/src/unistd/read.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for read --------------------------*- 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_UNISTD_READ_H
+#define LLVM_LIBC_SRC_UNISTD_READ_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+ssize_t read(int fd, void *buf, size_t count);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_READ_H
diff --git a/libc/test/src/unistd/CMakeLists.txt b/libc/test/src/unistd/CMakeLists.txt
@@ -1,14 +1,18 @@
 add_libc_testsuite(libc_unistd_unittests)
 
 add_libc_unittest(
-  write_test
+  read_write_test
   SUITE
     libc_unistd_unittests
   SRCS
-    write_test.cpp
+    read_write_test.cpp
   DEPENDS
     libc.include.errno
     libc.include.unistd
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.fsync
+    libc.src.unistd.read
     libc.src.unistd.write
     libc.test.errno_setter_matcher
 )
diff --git a/libc/test/src/unistd/read_write_test.cpp b/libc/test/src/unistd/read_write_test.cpp
@@ -0,0 +1,59 @@
+//===-- Unittests for read and write --------------------------------------===//
+//
+// 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/fcntl/open.h"
+#include "src/unistd/close.h"
+#include "src/unistd/fsync.h"
+#include "src/unistd/read.h"
+#include "src/unistd/write.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+
+TEST(LlvmLibcUniStd, WriteAndReadBackTest) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+  constexpr const char *TEST_FILE = "__unistd_read_write.test";
+  int write_fd = __llvm_libc::open(TEST_FILE, O_WRONLY | O_CREAT);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(write_fd, 0);
+  constexpr const char HELLO[] = "hello";
+  constexpr int HELLO_SIZE = sizeof(HELLO);
+  ASSERT_THAT(__llvm_libc::write(write_fd, HELLO, HELLO_SIZE),
+              Succeeds(HELLO_SIZE));
+  ASSERT_THAT(__llvm_libc::fsync(write_fd), Succeeds(0));
+  ASSERT_THAT(__llvm_libc::close(write_fd), Succeeds(0));
+
+  int read_fd = __llvm_libc::open(TEST_FILE, O_RDONLY);
+  ASSERT_EQ(errno, 0);
+  ASSERT_GT(read_fd, 0);
+  char read_buf[10];
+  ASSERT_THAT(__llvm_libc::read(read_fd, read_buf, HELLO_SIZE),
+              Succeeds(HELLO_SIZE));
+  EXPECT_STREQ(read_buf, HELLO);
+  ASSERT_THAT(__llvm_libc::close(read_fd), Succeeds(0));
+
+  // TODO: 'remove' the test file after the test.
+}
+
+TEST(LlvmLibcUniStd, WriteFails) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+
+  EXPECT_THAT(__llvm_libc::write(-1, "", 1), Fails(EBADF));
+  EXPECT_THAT(__llvm_libc::write(1, reinterpret_cast<const void *>(-1), 1),
+              Fails(EFAULT));
+}
+
+TEST(LlvmLibcUniStd, ReadFails) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+
+  EXPECT_THAT(__llvm_libc::read(-1, nullptr, 1), Fails(EBADF));
+  EXPECT_THAT(__llvm_libc::read(0, reinterpret_cast<void *>(-1), 1),
+              Fails(EFAULT));
+}
diff --git a/libc/test/src/unistd/write_test.cpp b/libc/test/src/unistd/write_test.cpp