auto import from //depot/cupcake/@135843
diff --git a/libc/stdlib/atexit.h b/libc/stdlib/atexit.h
new file mode 100644
index 0000000..1b23565
--- /dev/null
+++ b/libc/stdlib/atexit.h
@@ -0,0 +1,51 @@
+/* $OpenBSD: atexit.h,v 1.7 2007/09/03 14:40:16 millert Exp $ */
+
+/*
+ * Copyright (c) 2002 Daniel Hartmeier
+ * 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 HOLDERS 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.
+ *
+ */
+
+struct atexit {
+ struct atexit *next; /* next in list */
+ int ind; /* next index in this table */
+ int max; /* max entries >= ATEXIT_SIZE */
+ struct atexit_fn {
+ union {
+ void (*std_func)(void);
+ void (*cxa_func)(void *);
+ } fn_ptr;
+ void *fn_arg; /* argument for CXA callback */
+ void *fn_dso; /* shared module handle */
+ } fns[1]; /* the table itself */
+};
+
+extern int __atexit_invalid;
+extern struct atexit *__atexit; /* points to head of LIFO stack */
+
+int __cxa_atexit(void (*)(void *), void *, void *);
+void __cxa_finalize(void *);