diff --git a/libc/include/sys/epoll.h b/libc/include/sys/epoll.h
index 2091b90..2bad655 100644
--- a/libc/include/sys/epoll.h
+++ b/libc/include/sys/epoll.h
@@ -26,8 +26,12 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _SYS_EPOLL_H_
-#define _SYS_EPOLL_H_
+#pragma once
+
+/**
+ * @file sys/epoll.h
+ * @brief I/O event file descriptors.
+ */
 
 #include <sys/cdefs.h>
 #include <sys/types.h>
@@ -37,14 +41,67 @@
 
 __BEGIN_DECLS
 
+/**
+ * [epoll_create(2)](http://man7.org/linux/man-pages/man2/epoll_create.2.html)
+ * creates a new [epoll](http://man7.org/linux/man-pages/man7/epoll.7.html)
+ * file descriptor.
+ *
+ * Returns a new file descriptor on success and returns -1 and sets `errno` on
+ * failure.
+ */
 int epoll_create(int __size);
+
+/**
+ * [epoll_create1(2)](http://man7.org/linux/man-pages/man2/epoll_create1.2.html)
+ * creates a new [epoll](http://man7.org/linux/man-pages/man7/epoll.7.html)
+ * file descriptor with the given flags.
+ *
+ * Returns a new file descriptor on success and returns -1 and sets `errno` on
+ * failure.
+ */
 int epoll_create1(int __flags);
 
+/**
+ * [epoll_ctl(2)](http://man7.org/linux/man-pages/man2/epoll_ctl.2.html)
+ * adds/modifies/removes file descriptors from the given epoll file descriptor.
+ *
+ * Returns 0 on success and returns -1 and sets `errno` on failure.
+ */
 int epoll_ctl(int __epoll_fd, int __op, int __fd, struct epoll_event* __BIONIC_COMPLICATED_NULLNESS __event);
+
+/**
+ * [epoll_wait(2)](http://man7.org/linux/man-pages/man2/epoll_wait.2.html)
+ * waits for an event on the given epoll file descriptor.
+ *
+ * Returns the number of ready file descriptors on success, 0 on timeout,
+ * or -1 and sets `errno` on failure.
+ */
 int epoll_wait(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms);
+
+/**
+ * Like epoll_wait() but atomically applying the given signal mask.
+ */
 int epoll_pwait(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms, const sigset_t* _Nullable __mask);
+
+/**
+ * Like epoll_pwait() but using a 64-bit signal mask even on 32-bit systems.
+ *
+ * Available since API level 28.
+ */
 int epoll_pwait64(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28);
 
-__END_DECLS
+/**
+ * Like epoll_pwait() but with a `struct timespec` timeout, for nanosecond resolution.
+ *
+ * Available since API level 35.
+ */
+int epoll_pwait2(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, const struct timespec* _Nullable __timeout, const sigset_t* _Nullable __mask) __INTRODUCED_IN(35);
 
-#endif
+/**
+ * Like epoll_pwait2() but using a 64-bit signal mask even on 32-bit systems.
+ *
+ * Available since API level 35.
+ */
+int epoll_pwait2_64(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, const struct timespec* _Nullable __timeout, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(35);
+
+__END_DECLS