--- a/build/openldap.m4
+++ b/build/openldap.m4
@@ -243,6 +243,40 @@ OL_RESOLVER_TRY(ol_cv_resolver_none)
 OL_RESOLVER_TRY(ol_cv_resolver_resolv,[-lresolv])
 OL_RESOLVER_TRY(ol_cv_resolver_bind,[-lbind])
 ])
+
+dnl --------------------------------------------------------------------
+dnl Check for version compatility with back-mdb
+AC_DEFUN([OL_MDB_COMPAT],
+[AC_CACHE_CHECK([if LMDB version supported by MDB backends], [ol_cv_mdb_compat],[
+	AC_EGREP_CPP(__mdb_version_compat,[
+#include <lmdb.h>
+
+/* require 0.9.18 or later */
+#if MDB_VERSION_FULL >= 0x000000090012
+	__mdb_version_compat
+#endif
+	], [ol_cv_mdb_compat=yes], [ol_cv_mdb_compat=no])])
+])
+
+dnl
+dnl --------------------------------------------------------------------
+dnl Find any MDB
+AC_DEFUN([OL_MDB],
+[ol_cv_mdb=no
+AC_CHECK_HEADERS(lmdb.h)
+if test $ac_cv_header_lmdb_h = yes; then
+	OL_MDB_COMPAT
+
+	if test $ol_cv_mdb_compat != yes ; then
+		AC_MSG_ERROR([LMDB version incompatible with MDB backends])
+	fi
+
+	ol_cv_lib_mdb=-llmdb
+	ol_cv_mdb=yes
+fi
+])
+
+
 dnl
 dnl ====================================================================
 dnl Check POSIX Thread version 
--- a/build/top.mk
+++ b/build/top.mk
@@ -164,6 +164,7 @@ CLIENT_LIBS = @CLIENT_LIBS@
 LUTIL_LIBS = @LUTIL_LIBS@
 LTHREAD_LIBS = @LTHREAD_LIBS@
 
+MDB_LIBS = @MDB_LIBS@
 SLAPD_NDB_LIBS = @SLAPD_NDB_LIBS@
 WT_LIBS = @WT_LIBS@
 
--- a/configure.ac
+++ b/configure.ac
@@ -547,6 +547,7 @@ AC_MSG_RESULT(done)
 dnl ----------------------------------------------------------------
 dnl Initialize vars
 LDAP_LIBS=
+MDB_LIBS=
 SLAPD_NDB_LIBS=
 SLAPD_NDB_INCS=
 LTHREAD_LIBS=
@@ -646,6 +647,32 @@ dnl Checks for programs
 
 AC_DEFINE(HAVE_MKVERSION, 1, [define this if you have mkversion])
 
+dnl ----------------------------------------------------------------
+ol_link_mdb=no
+
+AS_IF([test x$ol_enable_mdb != xno], [
+	OL_MDB
+
+	if test $ol_cv_mdb = no ; then
+		AC_MSG_ERROR(MDB: LMDB not available)
+	fi
+
+	AC_DEFINE(HAVE_MDB,1,
+		[define this if LMDB is available])
+
+	dnl $ol_cv_lib_mdb should be yes or -llmdb
+	dnl (it could be no, but that would be an error
+	if test $ol_cv_lib_mdb != yes ; then
+		MDB_LIBS="$MDB_LIBS $ol_cv_lib_mdb"
+	fi
+
+	SLAPD_LIBS="$SLAPD_LIBS \$(MDB_LIBS)"
+
+	ol_link_mdb=yes
+])
+
+dnl ----------------------------------------------------------------
+
 dnl ----------------------------------------------------------------
 dnl
 dnl Determine which C translator to use
@@ -3150,6 +3177,7 @@ dnl pwmods
 AC_SUBST(LDAP_LIBS)
 AC_SUBST(CLIENT_LIBS)
 AC_SUBST(SLAPD_LIBS)
+AC_SUBST(MDB_LIBS)
 AC_SUBST(BALANCER_LIBS)
 AC_SUBST(SLAPD_NDB_LIBS)
 AC_SUBST(SLAPD_NDB_INCS)
--- a/servers/slapd/back-mdb/Makefile.in
+++ b/servers/slapd/back-mdb/Makefile.in
@@ -25,11 +25,10 @@ OBJS = init.lo tools.lo config.lo \
 	extended.lo operational.lo \
 	attr.lo index.lo key.lo filterindex.lo \
 	dn2entry.lo dn2id.lo id2entry.lo idl.lo \
-	nextid.lo monitor.lo mdb.lo midl.lo
+	nextid.lo monitor.lo
 
 LDAP_INCDIR= ../../../include       
 LDAP_LIBDIR= ../../../libraries
-MDB_SUBDIR = $(srcdir)/$(LDAP_LIBDIR)/liblmdb
 
 BUILD_OPT = "--enable-mdb"
 BUILD_MOD = @BUILD_MDB@
@@ -44,7 +43,7 @@ UNIX_LINK_LIBS = $(@BUILD_LIBS_DYNAMIC@_LDAP_LIBS)
 
 LIBBASE = back_mdb
 
-XINCPATH = -I.. -I$(srcdir)/.. -I$(MDB_SUBDIR)
+XINCPATH = -I.. -I$(srcdir)/..
 XDEFS = $(MODULES_CPPFLAGS)
 
 all-local-lib:	../.backend
@@ -52,11 +51,5 @@ all-local-lib:	../.backend
 ../.backend: lib$(LIBBASE).a
 	@touch $@
 
-mdb.lo:	$(MDB_SUBDIR)/mdb.c
-	$(LTCOMPILE_MOD) $(MDB_SUBDIR)/mdb.c
-
-midl.lo:	$(MDB_SUBDIR)/midl.c
-	$(LTCOMPILE_MOD) $(MDB_SUBDIR)/midl.c
-
 veryclean-local-lib: FORCE
 	$(RM) $(XXHEADERS) $(XXSRCS) .links