--- /tmp/ExternalProject.cmake	2016-04-26 17:36:20.000000000 -0400
+++ ExternalProject.cmake	2016-04-26 18:50:38.000000000 -0400
@@ -61,6 +61,9 @@
     The optional name of the remote, default to ``origin``
   ``GIT_SUBMODULES <module>...``
     Git submodules that shall be updated, all if empty
+  ``GIT_SHALLOW 1``
+    Instead of making full clone, only download most recent commit of repo
+    and its submodules
   ``HG_REPOSITORY <url>``
     URL of mercurial repo
   ``HG_TAG <tag>``
@@ -496,7 +499,7 @@
   "ExternalProject module."
   )
 
-function(_ep_write_gitclone_script script_filename source_dir git_EXECUTABLE git_repository git_tag git_remote_name git_submodules src_name work_dir gitclone_infofile gitclone_stampfile)
+function(_ep_write_gitclone_script script_filename source_dir git_EXECUTABLE git_repository git_tag git_remote_name git_submodules git_shallow src_name work_dir gitclone_infofile gitclone_stampfile)
   file(WRITE ${script_filename}
 "if(\"${git_tag}\" STREQUAL \"\")
   message(FATAL_ERROR \"Tag for git checkout should not be empty.\")
@@ -525,8 +528,16 @@
 set(error_code 1)
 set(number_of_tries 0)
 while(error_code AND number_of_tries LESS 3)
+  set(git_clone_command \"${git_EXECUTABLE}\" clone --origin \"${git_remote_name}\" \"${git_repository}\" \"${src_name}\")
+
+  if(${git_shallow})
+    list(APPEND git_clone_command --no-single-branch --depth 1)
+  endif()
+
+  message(\"\${git_clone_command}\")
+
   execute_process(
-    COMMAND \"${git_EXECUTABLE}\" clone --origin \"${git_remote_name}\" \"${git_repository}\" \"${src_name}\"
+    COMMAND \${git_clone_command}
     WORKING_DIRECTORY \"${work_dir}\"
     RESULT_VARIABLE error_code
     )
@@ -1774,6 +1785,11 @@
       set(git_remote_name "origin")
     endif()
 
+    get_property(git_shallow TARGET ${name} PROPERTY _EP_GIT_SHALLOW)
+    if(NOT git_shallow)
+      set(git_shallow 0)
+    endif()
+
     # For the download step, and the git clone operation, only the repository
     # should be recorded in a configured RepositoryInfo file. If the repo
     # changes, the clone script should be run again. But if only the tag
@@ -1797,7 +1813,7 @@
     # The script will delete the source directory and then call git clone.
     #
     _ep_write_gitclone_script(${tmp_dir}/${name}-gitclone.cmake ${source_dir}
-      ${GIT_EXECUTABLE} ${git_repository} ${git_tag} ${git_remote_name} "${git_submodules}" ${src_name} ${work_dir}
+      ${GIT_EXECUTABLE} ${git_repository} ${git_tag} ${git_remote_name} "${git_submodules}" ${git_shallow} ${src_name} ${work_dir}
       ${stamp_dir}/${name}-gitinfo.txt ${stamp_dir}/${name}-gitclone-lastrun.txt
       )
     set(comment "Performing download step (git clone) for '${name}'")