diff --git a/sys/cddl/compat/opensolaris/rpc/xdr.h b/sys/cddl/compat/opensolaris/rpc/xdr.h
new file mode 100644
index 000000000000..277e0c338f00
--- /dev/null
+++ b/sys/cddl/compat/opensolaris/rpc/xdr.h
@@ -0,0 +1,70 @@
+/*
+ * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
+ * unrestricted use provided that this legend is included on all tape
+ * media and as a part of the software program in whole or part.  Users
+ * may copy or modify Sun RPC without charge, but are not authorized
+ * to license or distribute it to anyone else except as part of a product or
+ * program developed by the user.
+ *
+ * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
+ * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
+ *
+ * Sun RPC is provided with no support and without any obligation on the
+ * part of Sun Microsystems, Inc. to assist in its use, correction,
+ * modification or enhancement.
+ *
+ * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
+ * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
+ * OR ANY PART THEREOF.
+ *
+ * In no event will Sun Microsystems, Inc. be liable for any lost revenue
+ * or profits or other special, indirect and consequential damages, even if
+ * Sun has been advised of the possibility of such damages.
+ *
+ * Sun Microsystems, Inc.
+ * 2550 Garcia Avenue
+ * Mountain View, California  94043
+ */
+
+#ifndef	_OPENSOLARIS_RPC_XDR_H_
+#define	_OPENSOLARIS_RPC_XDR_H_
+
+#include_next <rpc/xdr.h>
+
+#ifndef _KERNEL
+
+#include <assert.h>
+
+/*
+ * Taken from sys/xdr/xdr_mem.c.
+ *
+ * FreeBSD's userland XDR doesn't implement control method (only the kernel),
+ * but OpenSolaris nvpair still depend on it, so we have to implement it here.
+ */
+static __inline bool_t
+xdrmem_control(XDR *xdrs, int request, void *info)
+{
+	xdr_bytesrec *xptr;
+
+	switch (request) {
+	case XDR_GET_BYTES_AVAIL:
+		xptr = (xdr_bytesrec *)info;
+		xptr->xc_is_last_record = TRUE;
+		xptr->xc_num_avail = xdrs->x_handy;
+		return (TRUE);
+	default:
+		assert(!"unexpected request");
+	}
+	return (FALSE);
+}
+
+#undef XDR_CONTROL
+#define	XDR_CONTROL(xdrs, req, op)					\
+	(((xdrs)->x_ops->x_control == NULL) ?				\
+	    xdrmem_control((xdrs), (req), (op)) :			\
+	    (*(xdrs)->x_ops->x_control)(xdrs, req, op))   
+
+#endif	/* !_KERNEL */
+
+#endif	/* !_OPENSOLARIS_RPC_XDR_H_ */