auto import from //depot/cupcake/@135843
diff --git a/libc/stdlib/exit.c b/libc/stdlib/exit.c
new file mode 100644
index 0000000..83fe3d2
--- /dev/null
+++ b/libc/stdlib/exit.c
@@ -0,0 +1,59 @@
+/* $OpenBSD: exit.c,v 1.12 2007/09/03 14:40:16 millert Exp $ */
+/*-
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/types.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "atexit.h"
+#include "thread_private.h"
+
+/*
+ * This variable is zero until a process has created a thread.
+ * It is used to avoid calling locking functions in libc when they
+ * are not required. By default, libc is intended to be(come)
+ * thread-safe, but without a (significant) penalty to non-threaded
+ * processes.
+ */
+int __isthreaded = 0;
+
+/*
+ * Exit, flushing stdio buffers if necessary.
+ */
+void
+exit(int status)
+{
+ /*
+ * Call functions registered by atexit() or _cxa_atexit()
+ * (including the stdio cleanup routine) and then _exit().
+ */
+ __cxa_finalize(NULL);
+ _exit(status);
+}