diff --git a/bin/make_subspack b/bin/make_subspack
index b603a05..b5da484 100755
--- a/bin/make_subspack
+++ b/bin/make_subspack
@@ -12,6 +12,7 @@ get_from_bootstrap() {
 usage() {
         echo "usage: make_subspack [options] [-t|-u] path/to/existing/spack /path/to/new/area"
         echo " options are:"
+	echo "--without_caches       enable buildcache mirrors
         echo "--with_padding      enable directory padding in config"
         echo "--spack_release xx  install spack release xx"
         echo "--spack_repo url    use spack repo url"
@@ -32,7 +33,7 @@ parse_args() {
     verbose=false
     plain=false
 
-    if x=$(getopt --longoptions with_padding,spack_release:,spack_repo:,local_env:,dev_pkgs: --options vtup -- "$@")
+    if x=$(getopt --longoptions without_caches,with_padding,spack_release:,spack_repo:,local_env:,dev_pkgs: --options vtup -- "$@")
     then
         eval set : $x
         shift
@@ -44,6 +45,7 @@ parse_args() {
     while echo x$1 | grep x- > /dev/null
     do
         case "x$1" in
+        x--without_caches)  disable_caches=true; shift ;;
         x--with_padding)  padding=true; shift ;;
         x--spack_release) spack_release=$2; shift; shift;;
         x--spack_repo)    spack_repo=$2; shift; shift;;
@@ -304,7 +306,11 @@ message "Adding backup buildcache $binary_cache_bak"
 $SPACK_ROOT/bin/spack mirror add --scope site scisoft $binary_cache_bak
 $SPACK_ROOT/bin/spack buildcache update-index  -d $binary_cache_bak
 $SPACK_ROOT/bin/spack -k buildcache keys --install --trust --force
-
+if [ "$disable_caches" != "" ]
+then
+    echo "Disabling buildcache mirrors."
+    mv $SPACK_ROOT/etc/spack/mirrors.yaml $SPACK_ROOT/etc/spack/mirrors.yaml.bak
+fi
 #symlink in environments from upstream
 cd $SPACK_ROOT/var/spack
 mkdir environments