diff --git a/browser_patches/checkout_build_archive_upload.sh b/browser_patches/checkout_build_archive_upload.sh
index 070a8a78be..577840ca62 100755
--- a/browser_patches/checkout_build_archive_upload.sh
+++ b/browser_patches/checkout_build_archive_upload.sh
@@ -58,6 +58,8 @@ fi
 
 echo "-- preparing checkout"
 ./prepare_checkout.sh $BROWSER_NAME
+echo "-- cleaning"
+./$BROWSER_NAME/clean.sh
 echo "-- building"
 ./$BROWSER_NAME/build.sh
 echo "-- archiving to $ZIP_PATH"
diff --git a/browser_patches/firefox/clean.sh b/browser_patches/firefox/clean.sh
new file mode 100755
index 0000000000..89936dd0a1
--- /dev/null
+++ b/browser_patches/firefox/clean.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+set -e
+set +x
+
+trap "cd $(pwd -P)" EXIT
+cd "$(dirname $0)"
+cd "checkout"
+
+OBJ_FOLDER=$(ls -1 | grep obj-)
+if [[ -d $OBJ_FOLDER ]]; then
+  rm -rf $OBJ_FOLDER
+fi
+
diff --git a/browser_patches/webkit/clean.sh b/browser_patches/webkit/clean.sh
new file mode 100755
index 0000000000..876e7828cf
--- /dev/null
+++ b/browser_patches/webkit/clean.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+set -e
+set +x
+
+trap "cd $(pwd -P)" EXIT
+cd "$(dirname $0)"
+cd "checkout"
+
+rm -rf WebKitBuild