diff --git a/usr.sbin/pwd_mkdb/pwd_mkdb.8 b/usr.sbin/pwd_mkdb/pwd_mkdb.8
index 951d01177537..7c0bf43e7bdc 100644
--- a/usr.sbin/pwd_mkdb/pwd_mkdb.8
+++ b/usr.sbin/pwd_mkdb/pwd_mkdb.8
@@ -1,4 +1,4 @@
-.\"	$NetBSD: pwd_mkdb.8,v 1.21 2005/09/05 03:37:15 hubertf Exp $
+.\"	$NetBSD: pwd_mkdb.8,v 1.22 2006/09/23 17:17:04 sketch Exp $
 .\"
 .\" Copyright (c) 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -64,6 +64,13 @@ The options are as follows:
 Store data in big-endian format.
 .It Fl L
 Store data in little-endian format.
+.It Fl c Ar cachesize
+Specify in megabytes the size of the memory cache used by the hashing
+library.  On systems with a large user base, a small cache size can lead
+to prohibitively long database file rebuild times.  As a rough guide, the
+memory usage of pwd_mkdb in megabytes will be a little bit more than twice
+the figure specified here.  If unspecified, this value will be calculated
+based on the size of the input file up to a maximum of 8 megabytes.
 .It Fl d Ar directory
 Change the root directory of the generated files from
 .Dq Pa /
diff --git a/usr.sbin/pwd_mkdb/pwd_mkdb.c b/usr.sbin/pwd_mkdb/pwd_mkdb.c
index 5cd44b7b85f1..02ab14f08266 100644
--- a/usr.sbin/pwd_mkdb/pwd_mkdb.c
+++ b/usr.sbin/pwd_mkdb/pwd_mkdb.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: pwd_mkdb.c,v 1.30 2005/06/02 09:18:14 lukem Exp $	*/
+/*	$NetBSD: pwd_mkdb.c,v 1.31 2006/09/23 17:17:04 sketch Exp $	*/
 
 /*
  * Copyright (c) 1991, 1993, 1994
@@ -65,7 +65,7 @@ __COPYRIGHT("@(#) Copyright (c) 2000\n\
 Copyright (c) 1991, 1993, 1994\n\
 	The Regents of the University of California.  All rights reserved.\n");
 __SCCSID("from: @(#)pwd_mkdb.c	8.5 (Berkeley) 4/20/94");
-__RCSID("$NetBSD: pwd_mkdb.c,v 1.30 2005/06/02 09:18:14 lukem Exp $");
+__RCSID("$NetBSD: pwd_mkdb.c,v 1.31 2006/09/23 17:17:04 sketch Exp $");
 #endif /* not lint */
 
 #if HAVE_NBTOOL_CONFIG_H
@@ -162,8 +162,9 @@ main(int argc, char *argv[])
 	found = 0;
 	newuser = 0;
 	dp = NULL;
+	cachesize = 0;
 
-	while ((ch = getopt(argc, argv, "BLd:psu:v")) != -1)
+	while ((ch = getopt(argc, argv, "BLc:d:psu:v")) != -1)
 		switch (ch) {
 		case 'B':			/* big-endian output */
 			lorder = BIG_ENDIAN;
@@ -171,6 +172,9 @@ main(int argc, char *argv[])
 		case 'L':			/* little-endian output */
 			lorder = LITTLE_ENDIAN;
 			break;
+		case 'c':
+			cachesize = atoi(optarg) * 1024 * 1024;
+			break;
 		case 'd':			/* set prefix */
 			strlcpy(prefix, optarg, sizeof(prefix));
 			break;
@@ -230,13 +234,17 @@ main(int argc, char *argv[])
 	if (fstat(fileno(fp), &st) == -1)
 		error(pname);
 
-	/* Tweak openinfo values for large passwd files. */
-	cachesize = st.st_size * 20;
-	if (cachesize > MAX_CACHESIZE)
-		cachesize = MAX_CACHESIZE;
-	else if (cachesize < MIN_CACHESIZE)
-		cachesize = MIN_CACHESIZE;
-	openinfo.cachesize = cachesize;
+	if (cachesize) {
+		openinfo.cachesize = cachesize;
+	} else {
+		/* Tweak openinfo values for large passwd files. */
+		cachesize = st.st_size * 20;
+		if (cachesize > MAX_CACHESIZE)
+			cachesize = MAX_CACHESIZE;
+		else if (cachesize < MIN_CACHESIZE)
+			cachesize = MIN_CACHESIZE;
+		openinfo.cachesize = cachesize;
+	}
 
 	/* Open the temporary insecure password database. */
 	if (!secureonly) {
@@ -813,6 +821,6 @@ usage(void)
 {
 
 	(void)fprintf(stderr,
-	    "usage: pwd_mkdb [-BLps] [-d directory] [-u user] file\n");
+	    "usage: pwd_mkdb [-BLps] [-c cachesize] [-d directory] [-u user] file\n");
 	exit(EXIT_FAILURE);
 }