--- a/mail/configure.in
+++ b/mail/configure.in
@@ -87,15 +87,20 @@ if test -n "$COMPILE_ENVIRONMENT" -a -n 
     if test -n "$HAVE_64BIT_BUILD"; then
         dnl A 64-bit OS was (auto-)detected: (explicitly) enable 64-bit support.
         ac_configure_args="$ac_configure_args --enable-64bit"
     fi
     if test -n "$LIBXUL_SDK"; then
         ac_configure_args="$ac_configure_args --with-nspr=$LIBXUL_DIST"
     fi
 
+    dnl Explicitly disable the DEBUG RTL
+    if test -n "$MOZ_NO_DEBUG_RTL"; then
+      ac_configure_args="$ac_configure_args --disable-debug-rtl"
+    fi
+
     dnl The cache file needs to be an absolute path to work properly.
     cache_file_base=`dirname $cache_file`
     cache_file=`cd $cache_file_base && pwd`/`basename $cache_file`
 
     AC_OUTPUT_SUBDIRS(ldap/sdks/c-sdk)
     ac_configure_args="$_save_ac_configure_args"
 fi # COMPILE_ENVIRONMENT && MOZ_LDAP_XPCOM