diff --git a/Makefile b/Makefile
index 349938d..027660a 100644
--- a/Makefile
+++ b/Makefile
@@ -9,12 +9,16 @@
 SOURCEDIR    ?= .
 BUILDDIR     ?= _build
 
+# Other repos with documentation to include.
+# edit the `git_refs` file with the commit/tag/branch that you want to use
+OTHER_REPO_DOCS ?= bbsim voltha-go voltha-openolt-adapter voltha-openonu-adapter voltha-protos
+
 # Put it first so that "make" without argument is like "make help".
 help: doc_venv
 	source $</bin/activate ; set -u ;\
 	$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 
-.PHONY: help test lint reload Makefile
+.PHONY: help test lint reload Makefile prep
 
 # Create the virtualenv with all the tools installed
 doc_venv:
@@ -56,10 +60,6 @@
 clean-all: clean
 	rm -rf doc_venv repos
 
-# Other repos with documentation to include.
-# edit the `git_refs` file with the commit/tag/branch that you want to use
-OTHER_REPO_DOCS ?= bbsim voltha-go voltha-openolt-adapter voltha-openonu-adapter voltha-protos
-
 # checkout the repos inside repos/ dir
 repos:
 	mkdir repos
@@ -74,34 +74,44 @@
 # pre-populate it under repos/ with the specific commit to being validated
 SKIP_CHECKOUT   ?=
 
-# clone (only if doesn't exist), then checkout ref in repos/*
+# clone (only if doesn't exist)
 $(CHECKOUT_REPOS): | repos
-	GIT_REF=`grep '^$(@F) ' git_refs | awk '{print $$3}'` ;\
 	if [ ! -d '$@' ] ;\
 	  then git clone $(REPO_HOST)/$(@F) $@ ;\
-	fi ;\
-	if [ "$(SKIP_CHECKOUT)" = "$(@F)" ] ;\
-	  then echo "Skipping checkout of repo $(SKIP_CHECKOUT) as it's being tested" ;\
-	else pushd $@ ;\
-	  git checkout $$GIT_REF ;\
-	  popd ;\
 	fi
 
-# link subdirectories (if applicable) into main docs dir
+# link subdirectories (if applicable) into main docs dir, then checkout ref if
+# not under test
 $(OTHER_REPO_DOCS): | $(CHECKOUT_REPOS)
 	GIT_SUBDIR=`grep '^$@ ' git_refs | awk '{print $$2}'` ;\
-	ln -s repos/$(@)$$GIT_SUBDIR $@
+	ln -s repos/$(@)$$GIT_SUBDIR $@ ;\
+	if [ "$(SKIP_CHECKOUT)" != "$@" ] ;\
+	  then GIT_REF=`grep '^$@ ' git_refs | awk '{print $$3}'` ;\
+	  pushd $@ ;\
+	    git checkout $$GIT_REF ;\
+	  popd ;\
+	fi
 
 # generate a list of git checksums suitable for updating git_refs
 freeze: repos
 	@for repo in $(OTHER_REPO_DOCS) ; do \
 	  GIT_SUBDIR=`grep "^$$repo " git_refs | awk '{print $$2}'` ;\
-	  cd "repos/$$repo" > /dev/null ;\
+	  pushd "repos/$$repo" > /dev/null ;\
 	    HEAD_SHA=`git rev-parse HEAD` ;\
 	    printf "%-24s %-8s %-40s\n" $$repo $$GIT_SUBDIR $$HEAD_SHA ;\
-	  cd ../.. ;\
+	  popd ;\
 	done
 
+# use sphinxcontrib-versioning to make a versioned copy of the
+# NOTE: document root is now in _build, not _build/html
+versioned: doc_venv Makefile | $(OTHER_REPO_DOCS)
+	source $</bin/activate ; set -u ;\
+	sphinx-versioning build -r master "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
+
+# prep target - used in sphinxcontrib-versioning to create versioned repos when
+# building multiple versions
+prep: | $(OTHER_REPO_DOCS)
+
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: doc_venv Makefile | $(OTHER_REPO_DOCS)