diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index f5cc6722da..397451fd01 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1029,12 +1029,13 @@ unit:gcc:ossl3:amd64:
       artifacts: true
 
 # Jobs for regular GCC builds on Debian "sid" (amd64)
+# Also tests configration option: --without-lmdb.
 
 gcc:sid:amd64:
   variables:
     CC: gcc
     CFLAGS: "${CFLAGS_COMMON} -O3"
-    EXTRA_CONFIGURE: "--with-libidn2 ${WITH_READLINE}"
+    EXTRA_CONFIGURE: "--with-libidn2 --without-lmdb ${WITH_READLINE}"
     RUN_MAKE_INSTALL: 1
   <<: *debian_sid_amd64_image
   <<: *build_job
@@ -1055,13 +1056,14 @@ unit:gcc:sid:amd64:
       artifacts: true
 
 # Job for out-of-tree GCC build on Debian 12 "bookworm" (amd64)
+# Also tests configration option: --with-lmdb.
 
 gcc:out-of-tree:
   variables:
     CC: gcc
     CFLAGS: "${CFLAGS_COMMON} -Og"
     CONFIGURE: "${CI_PROJECT_DIR}/configure"
-    EXTRA_CONFIGURE: "--with-libidn2"
+    EXTRA_CONFIGURE: "--with-libidn2 --with-lmdb"
     RUN_MAKE_INSTALL: 1
     OUT_OF_TREE_WORKSPACE: workspace
   <<: *base_image
diff --git a/configure.ac b/configure.ac
index 5cb7651d62..276ac0f8d3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -756,13 +756,49 @@ AC_SUBST([KRB5_CFLAGS])
 AC_SUBST([KRB5_LIBS])
 
 #
-# LMDB is mandatory
+# LMDB is mandatory, BIND9 source code provides an LMDB implementation
+# if LMDB not installed on the OS
 #
-PKG_CHECK_MODULES([LMDB], [lmdb])
-AX_SAVE_FLAGS([lmdb])
+# `--with-lmdb=auto` picks the OS version if installed, or the
+#                    provided version otherwise.
+# `--with-lmdb=yes` picks the OS version, fails if not installed.
+# `--without-lmdb` picks the provided version.
+#
+# [pairwise: --with-lmdb=auto, --with-lmdb=yes, --without-lmdb]
+#
+AC_ARG_WITH([lmdb],
+	    [AS_HELP_STRING([--with-lmdb=@<:@PATH@:>@],
+			    [use LMDB library @<:@default=auto@:>@, optionally specify the prefix for lmdb library])],
+	    [:],
+	    [with_lmdb="auto"])
 
-CFLAGS="$CFLAGS $LMDB_CFLAGS"
-LIBS="$LIBS $LMDB_LIBS"
+ac_lib_lmdb_found=no
+AS_CASE([$with_lmdb],
+	[no],[],
+	[auto|yes], [PKG_CHECK_MODULES([LMDB], [lmdb],
+				       [ac_lib_lmdb_found=yes],
+				       [for ac_lib_lmdb_path in /usr /usr/local /opt /opt/local; do
+						AX_LIB_LMDB([$ac_lib_lmdb_path],
+							    [ac_lib_lmdb_found=yes
+							     break])
+					done
+				       ])],
+	[AX_LIB_LMDB([$with_lmdb],[ac_lib_lmdb_found=yes])])
+
+# don't fail when in automatic mode
+AS_IF([test "$with_lmdb" = "auto" && test "$ac_lib_lmdb_found" = "no"],
+      [with_lmdb=no])
+
+# hard fail when LMDB requested, but not found
+AS_IF([test "$with_lmdb" != "no" && test "$ac_lib_lmdb_found" != "yes"],
+      [AC_MSG_ERROR([LMDB requested, but not found])])
+
+AS_IF([test "$ac_lib_lmdb_found" = "yes"],
+      [AC_DEFINE([HAVE_LMDB], [1], [Use lmdb library])])
+
+AC_SUBST([LMDB_CFLAGS])
+AC_SUBST([LMDB_LIBS])
+AM_CONDITIONAL([HAVE_LMDB], [test -n "$LMDB_LIBS"])
 
 #
 # was --with-libxml2 specified?
@@ -1489,6 +1525,7 @@ report() {
 	test -z "$LIBXML2_LIBS" || echo "    XML statistics (--with-libxml2)"
 	test -z "$JSON_C_LIBS" || echo "    JSON statistics (--with-json-c): $JSON_C_CFLAGS $JSON_C_LIBS"
 	test -z "$ZLIB_LIBS" || echo "    HTTP zlib compression (--with-zlib)"
+	test -z "$LMDB_LIBS" || echo "    LMDB database to store configurations (--with-lmdb)"
 	test -z "$LIBIDN2_LIBS" || echo "    IDN support (--with-libidn2)"
     fi
 
@@ -1550,6 +1587,7 @@ report() {
     test -z "$LIBXML2_LIBS" && echo "    XML statistics (--with-libxml2)"
     test -z "$JSON_C_LIBS" && echo "    JSON statistics (--with-json-c)"
     test -z "$ZLIB_LIBS" && echo "    HTTP zlib compression (--with-zlib)"
+    test -z "$LMDB_LIBS" && echo "    LMDB database to store configurations (--with-lmdb)"
     test -z "$LIBIDN2_LIBS" && echo "    IDN support (--with-libidn2)"
 
     echo "-------------------------------------------------------------------------------"
diff --git a/lib/isc/Makefile.am b/lib/isc/Makefile.am
index 98a3525522..214b460252 100644
--- a/lib/isc/Makefile.am
+++ b/lib/isc/Makefile.am
@@ -216,7 +216,6 @@ libisc_la_CPPFLAGS =		\
 	$(AM_CPPFLAGS)		\
 	$(LIBISC_CFLAGS)	\
 	$(LIBUV_CFLAGS)		\
-	$(LMDB_CFLAGS)		\
 	$(OPENSSL_CFLAGS)	\
 	$(ZLIB_CFLAGS)
 
@@ -226,7 +225,6 @@ libisc_la_LDFLAGS =		\
 
 libisc_la_LIBADD =		\
 	$(LIBUV_LIBS)		\
-	$(LMDB_LIBS)		\
 	$(OPENSSL_LIBS)		\
 	$(ZLIB_LIBS)
 
@@ -265,6 +263,18 @@ libisc_la_LIBADD +=		\
 	$(LIBXML2_LIBS)
 endif HAVE_LIBXML2
 
+if HAVE_LMDB
+libisc_la_CPPFLAGS +=		\
+	$(LMDB_CFLAGS)
+libisc_la_LDFLAGS +=		\
+	$(LMDB_LIBS)
+else
+libisc_la_SOURCES +=		\
+	openldap-lmdb/mdb.c
+libisc_la_SOURCES +=		\
+	openldap-lmdb/midl.c
+endif
+
 if !HAVE_SYSTEMTAP
 DTRACE_DEPS = libisc_la-rwlock.lo libisc_la-job.lo
 DTRACE_OBJS = .libs/libisc_la-rwlock.$(OBJEXT) .libs/libisc_la-job.$(OBJEXT)
diff --git a/lib/isc/include/isc/lmdb.h b/lib/isc/include/isc/lmdb.h
index 391303c24f..e31bfc3c16 100644
--- a/lib/isc/include/isc/lmdb.h
+++ b/lib/isc/include/isc/lmdb.h
@@ -13,7 +13,11 @@
 
 #pragma once
 
+#ifdef HAVE_LMDB
 #include <lmdb.h>
+#else
+#include "../../openldap-lmdb/lmdb.h"
+#endif
 
 #define DNS_LMDB_COMMON_FLAGS (MDB_NOSUBDIR | MDB_NOLOCK)
 #ifndef __OpenBSD__
diff --git a/lib/isc/include/isc/openldap-lmdb.h b/lib/isc/openldap-lmdb/lmdb.h
similarity index 99%
rename from lib/isc/include/isc/openldap-lmdb.h
rename to lib/isc/openldap-lmdb/lmdb.h
index 199382a14c..f68dbe7608 100644
--- a/lib/isc/include/isc/openldap-lmdb.h
+++ b/lib/isc/openldap-lmdb/lmdb.h
@@ -1,3 +1,16 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the OpenLDAP
+ * Public License. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See license comment below for additional information regarding
+ * copyright ownership.
+ */
+
 /** @file lmdb.h
  *	@brief Lightning memory-mapped database library
  *
diff --git a/lib/isc/lmdb/mdb.c b/lib/isc/openldap-lmdb/mdb.c
similarity index 99%
rename from lib/isc/lmdb/mdb.c
rename to lib/isc/openldap-lmdb/mdb.c
index 668f9660f2..df64c6c5f9 100644
--- a/lib/isc/lmdb/mdb.c
+++ b/lib/isc/openldap-lmdb/mdb.c
@@ -1,3 +1,16 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the OpenLDAP
+ * Public License. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See license comment below for additional information regarding
+ * copyright ownership.
+ */
+
 /** @file mdb.c
  *	@brief Lightning memory-mapped database library
  *
diff --git a/lib/isc/lmdb/midl.c b/lib/isc/openldap-lmdb/midl.c
similarity index 94%
rename from lib/isc/lmdb/midl.c
rename to lib/isc/openldap-lmdb/midl.c
index dc3a1f578c..a0476ef602 100644
--- a/lib/isc/lmdb/midl.c
+++ b/lib/isc/openldap-lmdb/midl.c
@@ -1,3 +1,16 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the OpenLDAP
+ * Public License. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See license comment below for additional information regarding
+ * copyright ownership.
+ */
+
 /**	@file midl.c
  *	@brief ldap bdb back-end ID List functions */
 /* $OpenLDAP$ */
diff --git a/lib/isc/lmdb/midl.h b/lib/isc/openldap-lmdb/midl.h
similarity index 93%
rename from lib/isc/lmdb/midl.h
rename to lib/isc/openldap-lmdb/midl.h
index 1abdc8af2a..113ee9d3ed 100644
--- a/lib/isc/lmdb/midl.h
+++ b/lib/isc/openldap-lmdb/midl.h
@@ -1,3 +1,16 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the OpenLDAP
+ * Public License. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See license comment below for additional information regarding
+ * copyright ownership.
+ */
+
 /**	@file midl.h
  *	@brief LMDB ID List header file.
  *