diff --git a/libc/include/sys/io.h b/libc/include/sys/io.h
new file mode 100644
index 0000000..d187b78
--- /dev/null
+++ b/libc/include/sys/io.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2024 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.
+ */
+
+#pragma once
+
+/**
+ * @file sys/io.h
+ * @brief The x86/x86-64 I/O port functions iopl() and ioperm().
+ */
+
+#include <sys/cdefs.h>
+
+#include <errno.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+__BEGIN_DECLS
+
+/**
+ * [iopl(2)](http://man7.org/linux/man-pages/man2/iopl.2.html) changes the I/O
+ * privilege level for all x86/x8-64 I/O ports, for the calling thread.
+ *
+ * New callers should use ioperm() instead.
+ *
+ * Returns 0 on success, and returns -1 and sets `errno` on failure.
+ *
+ * Only available for x86/x86-64.
+ */
+#if defined(__NR_iopl)
+__attribute__((__deprecated__("use ioperm() instead"))) static __inline int iopl(int __level) {
+  return syscall(__NR_iopl, __level);
+}
+#endif
+
+/**
+ * [ioperm(2)](http://man7.org/linux/man-pages/man2/ioperm.2.html) sets the I/O
+ * permissions for the given number of x86/x86-64 I/O ports, starting at the
+ * given port.
+ *
+ * Returns 0 on success, and returns -1 and sets `errno` on failure.
+ *
+ * Only available for x86/x86-64.
+ */
+#if defined(__NR_iopl)
+static __inline int ioperm(unsigned long __from, unsigned long __n, int __enabled) {
+  return syscall(__NR_ioperm, __from, __n, __enabled);
+}
+#endif
+
+__END_DECLS
diff --git a/tests/Android.bp b/tests/Android.bp
index 9aca488..656be1f 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -474,6 +474,7 @@
         "sys_cachectl_test.cpp",
         "sys_epoll_test.cpp",
         "sys_hwprobe_test.cpp",
+        "sys_io_test.cpp",
         "sys_mman_test.cpp",
         "sys_msg_test.cpp",
         "sys_param_test.cpp",
diff --git a/tests/sys_io_test.cpp b/tests/sys_io_test.cpp
new file mode 100644
index 0000000..293ceb2
--- /dev/null
+++ b/tests/sys_io_test.cpp
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2024 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 <gtest/gtest.h>
+
+#include <sys/io.h>
+
+#include "utils.h"
+
+TEST(sys_io, iopl) {
+#if defined(__i386__) || defined(__x86_64__)
+  errno = 0;
+  ASSERT_EQ(-1, iopl(4));
+  ASSERT_ERRNO(EINVAL);
+#else
+  GTEST_SKIP() << "iopl requires x86/x86-64";
+#endif
+}
+
+TEST(sys_io, ioperm) {
+#if defined(__i386__) || defined(__x86_64__)
+  errno = 0;
+  ASSERT_EQ(-1, ioperm(65535, 4, 0));
+  ASSERT_ERRNO(EINVAL);
+#else
+  GTEST_SKIP() << "ioperm requires x86/x86-64";
+#endif
+}