diff --git a/build_packages b/build_packages
index 402340e456..e4fb387690 100755
--- a/build_packages
+++ b/build_packages
@@ -72,6 +72,8 @@ DEFINE_boolean oldchromebinary "${FLAGS_FALSE}" \
   "Use the last prebuilt binary for Chrome produced by the buildbot."
 DEFINE_boolean skip_toolchain_update "${FLAGS_FALSE}" \
   "Don't update toolchain automatically."
+DEFINE_boolean skip_chroot_upgrade "${FLAGS_FALSE}" \
+  "Don't run the chroot upgrade automatically; use with care."
 
 # The --reuse_pkgs_from_local_boards flag tells Portage to share binary
 # packages between boards that are built locally, so that the total time
@@ -81,7 +83,6 @@ DEFINE_boolean skip_toolchain_update "${FLAGS_FALSE}" \
 DEFINE_boolean reuse_pkgs_from_local_boards $FLAGS_FALSE \
   "Bootstrap from local packages instead of remote packages."
 
-
 # Parse command line
 FLAGS_HELP="usage: $0 [flags]"
 FLAGS "$@" || exit 1
@@ -150,6 +151,10 @@ fi
 if [ "${FLAGS_skip_toolchain_update}" -eq "${FLAGS_TRUE}" ]; then
   UPDATE_ARGS+=" --skip_toolchain_update"
 fi
+if [ "${FLAGS_skip_chroot_upgrade}" -eq "${FLAGS_TRUE}" ]; then
+  UPDATE_ARGS+=" --skip_chroot_upgrade"
+fi
+
 ${SCRIPTS_DIR}/setup_board --quiet --board=${FLAGS_board} ${UPDATE_ARGS}
 
 if [ "${FLAGS_noworkon}" -eq "${FLAGS_FALSE}" ]; then
diff --git a/setup_board b/setup_board
index 406e23115b..6949a01aa0 100755
--- a/setup_board
+++ b/setup_board
@@ -70,9 +70,7 @@ DEFINE_boolean skip_toolchain_update $FLAGS_FALSE \
 DEFINE_integer jobs -1 \
   "How many packages to build in parallel at maximum."
 DEFINE_boolean skip_chroot_upgrade $FLAGS_FALSE \
-  "Don't run the chroot upgrade automatically. \
-This should only be called by version hook scripts that need to call \
-setup_board."
+  "Don't run the chroot upgrade automatically; use with care."
 
 # The --reuse_pkgs_from_local_boards flag tells Portage to share binary
 # packages between boards that are built locally, so that the total time