diff --git a/doc/man/man5/slapo-auditlog.5 b/doc/man/man5/slapo-auditlog.5
new file mode 100644
index 0000000000000000000000000000000000000000..2ab9b296114261dc865b35bcede763ace6abf5e7
--- /dev/null
+++ b/doc/man/man5/slapo-auditlog.5
@@ -0,0 +1,37 @@
+.TH SLAPO-AUDITLOG 5 "RELEASEDATE" "OpenLDAP LDVERSION"
+.\" Copyright 2005 The OpenLDAP Foundation All Rights Reserved.
+.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
+.\" $OpenLDAP$
+.SH NAME
+slapo-auditlog \- Audit Logging overlay
+.SH SYNOPSIS
+ETCDIR/slapd.conf
+.SH DESCRIPTION
+The Audit Logging overlay can be used to record all changes on a given
+backend database to a specified log file. Changes are logged as standard
+LDIF, with an additional comment header giving the timestamp of the change
+and the identity of the user making the change.
+.LP
+For Add and Modify operations the identity comes from the modifiersName
+associated with the operation. This is usually the same as the requestor's
+identity, but may be set by other overlays to reflect other values.
+.SH CONFIGURATION
+This
+.B slapd.conf
+option applies to the Audit Logging overlay.
+It should appear after the
+.B overlay
+directive and before any subsequent
+.B database
+directive.
+.TP
+.B auditlog <filename>
+Specify the fully qualified path for the log file.
+.TP
+.B
+.SH FILES
+.TP
+ETCDIR/slapd.conf
+default slapd configuration file
+.SH SEE ALSO
+.BR slapd.conf (5).
diff --git a/servers/slapd/overlays/auditlog.c b/servers/slapd/overlays/auditlog.c
new file mode 100644
index 0000000000000000000000000000000000000000..41da39cbc8510498efdc2c22a65cc02c15faaff4
--- /dev/null
+++ b/servers/slapd/overlays/auditlog.c
@@ -0,0 +1,236 @@
+/* auditlog.c - log modifications for audit/history purposes */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2005 The OpenLDAP Foundation.
+ * Portions copyright 2004-2005 Symas Corporation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Symas Corp. for inclusion in
+ * OpenLDAP Software.  This work was sponsored by Hewlett-Packard.
+ */
+
+#include "portable.h"
+
+#ifdef SLAPD_OVER_AUDITLOG
+
+#include <stdio.h>
+
+#include <ac/string.h>
+#include <ac/ctype.h>
+
+#include "slap.h"
+#include "ldif.h"
+
+typedef struct auditlog_data {
+	ldap_pvt_thread_mutex_t ad_mutex;
+	char *ad_logfile;
+} auditlog_data;
+
+int fprint_ldif(FILE *f, char *name, char *val, ber_len_t len) {
+	char *s;
+	if((s = ldif_put(LDIF_PUT_VALUE, name, val, len)) == NULL)
+		return(-1);
+	fputs(s, f);
+	ber_memfree(s);
+	return(0);
+}
+
+int auditlog_response(Operation *op, SlapReply *rs) {
+	slap_overinst *on = (slap_overinst *)op->o_bd->bd_info;
+	auditlog_data *ad = on->on_bi.bi_private;
+	FILE *f;
+	Attribute *a;
+	Modifications *m;
+	struct berval *b;
+	char *what, *subop, *suffix, *who = NULL;
+	long stamp = slap_get_time();
+	int i;
+
+	if ( rs->sr_err != LDAP_SUCCESS ) return SLAP_CB_CONTINUE;
+
+	if ( !op->o_bd || !ad->ad_logfile ) return SLAP_CB_CONTINUE;
+
+/*
+** add or modify: use modifiersName if present
+**
+*/
+	switch(op->o_tag) {
+		case LDAP_REQ_MODRDN:	what = "modrdn";	break;
+		case LDAP_REQ_DELETE:	what = "delete";	break;
+		case LDAP_REQ_ADD:
+			what = "add";
+			for(a = op->ora_e->e_attrs; a; a = a->a_next)
+				if( a->a_desc == slap_schema.si_ad_modifiersName ) {
+					who = a->a_vals[0].bv_val;
+					break;
+				}
+			break;
+		case LDAP_REQ_MODIFY:
+			what = "modify";
+			for(m = op->orm_modlist; m; m = m->sml_next)
+				if( m->sml_desc == slap_schema.si_ad_modifiersName ) {
+					who = m->sml_values[0].bv_val;
+					break;
+				}
+			break;
+		default:
+			return SLAP_CB_CONTINUE;
+	}
+
+	suffix = op->o_bd->be_suffix[0].bv_len ? op->o_bd->be_suffix[0].bv_val :
+		"global";
+
+/*
+** note: this means requestor's dn when modifiersName is null
+*/
+	if ( !who )
+		who = op->o_dn.bv_val;
+
+	ldap_pvt_thread_mutex_lock(&ad->ad_mutex);
+	if((f = fopen(ad->ad_logfile, "a")) == NULL) {
+		ldap_pvt_thread_mutex_unlock(&ad->ad_mutex);
+		return SLAP_CB_CONTINUE;
+	}
+
+	fprintf(f, "# %s %ld %s%s%s\ndn: %s\nchangetype: %s\n",
+		what, stamp, suffix, who ? " " : "", who ? who : "",
+		op->o_req_dn.bv_val, what);
+
+	switch(op->o_tag) {
+	  case LDAP_REQ_ADD:
+		for(a = op->ora_e->e_attrs; a; a = a->a_next)
+		    if(b = a->a_vals)
+			for(i = 0; b[i].bv_val; i++)
+				fprint_ldif(f, a->a_desc->ad_cname.bv_val, b[i].bv_val, b[i].bv_len);
+		break;
+
+	  case LDAP_REQ_MODIFY:
+		for(m = op->orm_modlist; m; m = m->sml_next) {
+			switch(m->sml_op & LDAP_MOD_OP) {
+				case LDAP_MOD_ADD:	 what = "add";		break;
+				case LDAP_MOD_REPLACE:	 what = "replace";	break;
+				case LDAP_MOD_DELETE:	 what = "delete";	break;
+				case LDAP_MOD_INCREMENT: what = "increment";	break;
+				default:
+					fprintf(f, "# MOD_TYPE_UNKNOWN:%02x\n", m->sml_op & LDAP_MOD_OP);
+					continue;
+			}
+			fprintf(f, "%s: %s\n", what, m->sml_desc->ad_cname.bv_val);
+			if(b = m->sml_values) for(i = 0; b[i].bv_val; i++)
+				fprint_ldif(f, m->sml_desc->ad_cname.bv_val, b[i].bv_val, b[i].bv_len);
+			fprintf(f, "-\n");
+		}
+		break;
+
+	  case LDAP_REQ_MODRDN:
+		fprintf(f, "newrdn: %s\ndeleteoldrdn: %s\n",
+			op->orr_newrdn.bv_val, op->orr_deleteoldrdn ? "1" : "0");
+		if(op->orr_newSup) fprintf(f, "newsuperior: %s\n", op->orr_newSup->bv_val);
+		break;
+
+	  case LDAP_REQ_DELETE:
+		/* nothing else needed */
+		break;
+	}
+
+	fprintf(f, "# end %s %ld\n\n", what, stamp);
+
+	fclose(f);
+	ldap_pvt_thread_mutex_unlock(&ad->ad_mutex);
+	return SLAP_CB_CONTINUE;
+}
+
+static slap_overinst auditlog;
+
+static int
+auditlog_db_init(
+	BackendDB *be
+)
+{
+	slap_overinst *on = (slap_overinst *)be->bd_info;
+	auditlog_data *ad = ch_malloc(sizeof(auditlog_data));
+
+	on->on_bi.bi_private = ad;
+	ldap_pvt_thread_mutex_init( &ad->ad_mutex );
+	return 0;
+}
+
+static int
+auditlog_db_close(
+	BackendDB *be
+)
+{
+	slap_overinst *on = (slap_overinst *)be->bd_info;
+	auditlog_data *ad = on->on_bi.bi_private;
+
+	free( ad->ad_logfile );
+	ad->ad_logfile = NULL;
+}
+
+static int
+auditlog_db_destroy(
+	BackendDB *be
+)
+{
+	slap_overinst *on = (slap_overinst *)be->bd_info;
+	auditlog_data *ad = on->on_bi.bi_private;
+
+	ldap_pvt_thread_mutex_destroy( &ad->ad_mutex );
+	free( ad );
+}
+
+static int
+auditlog_config(
+	BackendDB	*be,
+	const char	*fname,
+	int		lineno,
+	int		argc,
+	char	**argv
+)
+{
+	slap_overinst *on = (slap_overinst *) be->bd_info;
+	auditlog_data *ad = on->on_bi.bi_private;
+
+	/* history log file */
+	if ( strcasecmp( argv[0], "auditlog" ) == 0 ) {
+		if ( argc < 2 ) {
+			Debug( LDAP_DEBUG_ANY,
+	    "%s: line %d: missing filename in \"auditlog <filename>\" line\n",
+			    fname, lineno, 0 );
+				return( 1 );
+		}
+		ad->ad_logfile = ch_strdup( argv[1] );
+		return 0;
+	}
+	return SLAP_CONF_UNKNOWN;
+}
+
+int auditlog_init() {
+
+	auditlog.on_bi.bi_type = "auditlog";
+	auditlog.on_bi.bi_db_init = auditlog_db_init;
+	auditlog.on_bi.bi_db_config = auditlog_config;
+	auditlog.on_bi.bi_db_close = auditlog_db_close;
+	auditlog.on_bi.bi_db_destroy = auditlog_db_destroy;
+	auditlog.on_response = auditlog_response;
+
+	return overlay_register(&auditlog);
+}
+
+#if SLAPD_OVER_AUDITLOG == SLAPD_MOD_DYNAMIC && defined(PIC)
+int init_module( int argc, char *argv[]) {
+	return auditlog_init();
+}
+#endif
+
+#endif /* SLAPD_OVER_AUDITLOG */