Index: contrib/elftoolchain/libdwarf/zlib_stub.c
===================================================================
--- /dev/null
+++ contrib/elftoolchain/libdwarf/zlib_stub.c
@@ -0,0 +1,27 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 The FreeBSD Foundation
+ *
+ * This software was developed by Mark Johnston under sponsorship from
+ * the FreeBSD Foundation.
+ */
+
+#include <sys/cdefs.h>
+
+/*
+ * A hack to allow libdwarf.a to be statically linked without zlib.  This is
+ * unfortunately required for FreeBSD <= 13.0 to bootstrap build tools
+ * such as nm(1), as they use metadata from the source tree to generate the
+ * dependency list but then link with the build host's libraries.
+ */
+
+extern int uncompress(void *, unsigned long *, const void *,
+    unsigned long);
+
+int __weak_symbol
+uncompress(void *dst __unused, unsigned long *dstsz __unused,
+    const void *src __unused, unsigned long srcsz __unused)
+{
+	return (-6); /* Z_VERSION_ERROR */
+}
Index: lib/libdwarf/Makefile
===================================================================
--- lib/libdwarf/Makefile
+++ lib/libdwarf/Makefile
@@ -73,7 +73,8 @@
 	libdwarf_reloc.c	\
 	libdwarf_rw.c		\
 	libdwarf_sections.c	\
-	libdwarf_str.c
+	libdwarf_str.c		\
+	zlib_stub.c
 
 INCS=		dwarf.h libdwarf.h