diff --git a/tools/aospify_device.sh b/tools/aospify_device.sh
new file mode 100755
index 0000000..f25ac9d
--- /dev/null
+++ b/tools/aospify_device.sh
@@ -0,0 +1,164 @@
+#!/bin/bash
+
+# Script to swap core networking modules in a GMS userdebug device to AOSP modules, by remounting
+# the system partition and replacing module prebuilts. This is only to be used for local testing,
+# and should only be used on userdebug devices that support "adb root" and remounting the system
+# partition using overlayfs.
+#
+# Usage: aospify_device.sh [device_serial]
+# Reset by wiping data (adb reboot bootloader && fastboot erase userdata && fastboot reboot).
+#
+# This applies to NetworkStack, CaptivePortalLogin, dnsresolver, tethering, cellbroadcast modules,
+# which generally need to be preloaded together (core networking modules + cellbroadcast which
+# shares its certificates with NetworkStack and CaptivePortalLogin)
+#
+# This allows device manufacturers to test their changes in AOSP modules, running them on their
+# own device builds, before contributing contributing the patches to AOSP. After running this script
+# once AOSP modules can be quickly built and updated on the prepared device with:
+#   m NetworkStack
+#   adb install --staged $ANDROID_PRODUCT_OUT/system/priv-app/NetworkStack/NetworkStack.apk \
+#   adb reboot
+# or for APEX modules:
+#   m com.android.tethering deapexer
+#   $ANDROID_HOST_OUT/bin/deapexer decompress --input $ANDROID_PRODUCT_OUT/system/apex/com.android.tethering.capex --output /tmp/decompressed.apex
+#   adb install /tmp/decompressed.apex && adb reboot
+#
+# This has been tested on Android T and Android U Pixel devices. On recent (U+) devices, it requires
+# setting a released target SDK (for example target_sdk_version: "34") in
+# packages/modules/Connectivity/service/ServiceConnectivityResources/Android.bp before building.
+set -e
+
+function push_apex {
+    local original_apex_name=$1
+    local aosp_apex_name=$2
+    if $ADB_CMD shell ls /system/apex/$original_apex_name.capex 1>/dev/null 2>/dev/null; then
+        $ADB_CMD shell rm /system/apex/$original_apex_name.capex
+        $ADB_CMD push $ANDROID_PRODUCT_OUT/system/apex/$aosp_apex_name.capex /system/apex/
+    else
+        rm -f /tmp/decompressed_$aosp_apex_name.apex
+        $ANDROID_HOST_OUT/bin/deapexer decompress --input $ANDROID_PRODUCT_OUT/system/apex/$aosp_apex_name.capex --output /tmp/decompressed_$aosp_apex_name.apex
+        $ADB_CMD shell rm /system/apex/$original_apex_name.apex
+        $ADB_CMD push /tmp/decompressed_$aosp_apex_name.apex /system/apex/$aosp_apex_name.apex
+        rm /tmp/decompressed_$aosp_apex_name.apex
+    fi
+}
+
+function push_apk {
+    local app_type=$1
+    local original_apk_name=$2
+    local aosp_apk_name=$3
+    $ADB_CMD shell rm /system/$app_type/$original_apk_name/$original_apk_name.apk
+    $ADB_CMD push $ANDROID_PRODUCT_OUT/system/$app_type/$aosp_apk_name/$aosp_apk_name.apk /system/$app_type/$original_apk_name/
+}
+
+NETWORKSTACK_AOSP_SEPOLICY_KEY="<signer signature=\"308205dc308203c4a003020102020900fc6cb0d8a6fdd16\
+8300d06092a864886f70d01010b0500308181310b30090603550406130255533113301106035504080c0a43616c69666f72\
+6e69613116301406035504070c0d4d6f756e7461696e20566965773110300e060355040a0c07416e64726f69643110300e0\
+60355040b0c07416e64726f69643121301f06035504030c18636f6d2e616e64726f69642e6e6574776f726b737461636b30\
+20170d3139303231323031343632305a180f34373537303130383031343632305a308181310b30090603550406130255533\
+113301106035504080c0a43616c69666f726e69613116301406035504070c0d4d6f756e7461696e20566965773110300e06\
+0355040a0c07416e64726f69643110300e060355040b0c07416e64726f69643121301f06035504030c18636f6d2e616e647\
+26f69642e6e6574776f726b737461636b30820222300d06092a864886f70d01010105000382020f003082020a0282020100\
+bb71f5137ff0b2d757acc2ca3d378e0f8de11090d5caf3d49e314d35c283b778b02d792d8eba440364ca970985441660f0b\
+c00afbc63dd611b1bf51ad28a1edd21e0048f548b80f8bd113e25682822f57dab8273afaf12c64d19a0c6be238f3e66ddc7\
+9b10fd926931e3ee60a7bf618644da3c2c4fc428139d45d27beda7fe45e30075b493ead6ec01cdd55d931c0a657e2e59742\
+ca632b6dc3842a2deb7d22443c809291d7a549203ae6ae356582a4ca23f30f0549c4ec8408a75278e95c69e8390ad5280bc\
+efaef6f1309a41bd9f3bfb5d12dca7e79ec6fd6848193fa9ab728224887b4f93e985ec7cbf6401b0e863a4b91c05d046f04\
+0fe954004b1645954fcb4114cee1e8b64b47d719a19ef4c001cb183f7f3e166e43f56d68047c3440da34fdf529d44274b8b\
+2f6afb345091ad8ad4b93bd5c55d52286a5d3c157465db8ddf62e7cdb6b10fb18888046afdd263ae6f2125d9065759c7e42\
+f8610a6746edbdc547d4301612eeec3c3cbd124dececc8d38b20e73b13f24ee7ca13a98c5f61f0c81b07d2b519749bc2bcb\
+9e0949aef6c118a3e8125e6ab57fce46bb091a66740e10b31c740b891900c0ecda9cc69ecb4f3369998b175106dd0a4ffd7\
+024eb7e75fedd1a5b131d0bb2b40c63491e3cf86b8957b21521b3a96ed1376a51a6ac697866b0256dee1bcd9ab9a188bf4c\
+ed80b59a5f24c2da9a55eb7b0e502116e30203010001a3533051301d0603551d0e041604149383c92cfbf099d5c47b0c365\
+7d8622a084b72e1301f0603551d230418301680149383c92cfbf099d5c47b0c3657d8622a084b72e1300f0603551d130101\
+ff040530030101ff300d06092a864886f70d01010b050003820201006a0501382fde2a6b8f70c60cd1b8ee4f788718c288b\
+170258ef3a96230b65005650d6a4c42a59a97b2ddec502413e7b438fbd060363d74b74a232382a7f77fd3da34e38f79fad0\
+35a8b472c5cff365818a0118d87fa1e31cc7ed4befd27628760c290980c3cc3b7ff0cfd01b75ff1fcc83e981b5b25a54d85\
+b68a80424ac26015fb3a4c754969a71174c0bc283f6c88191dced609e245f5938ffd0ad799198e2d0bf6342221c1b0a5d33\
+2ed2fffc668982cabbcb7d3b630ff8476e5c84ac0ad37adf9224035200039f95ec1fa95bf83796c0e8986135cee2dcaef19\
+0b249855a7e7397d4a0bf17ea63d978589c6b48118a381fffbd790c44d80233e2e35292a3b5533ca3f2cc173f85cf904adf\
+e2e4e2183dc1eba0ebae07b839a81ff1bc92e292550957c8599af21e9c0497b9234ce345f3f508b1cc872aa55ddb5e773c5\
+c7dd6577b9a8b6daed20ae1ff4b8206fd9f5c8f5a22ba1980bef01ae6fcb2659b97ad5b985fa81c019ffe008ddd9c8130c0\
+6fc6032b2149c2209fc438a7e8c3b20ce03650ad31c4ee48f169777a0ae182b72ca31b81540f61f167d8d7adf4f6bb2330f\
+f5c24037245000d8172c12ab5d5aa5890b8b12db0f0e7296264eb66e7f9714c31004649fb4b864005f9c43c80db3f6de52f\
+d44d6e2036bfe7f5807156ed5ab591d06fd6bb93ba4334ea2739af8b41ed2686454e60b666d10738bb7ba88001\">\
+<seinfo value=\"network_stack\"\/><\/signer>"
+
+DEVICE=$1
+ADB_CMD="adb -s $DEVICE"
+
+if [ -z "$DEVICE" ]; then
+    echo "Usage: aospify_device.sh [device_serial]"
+    exit 1
+fi
+
+if [ -z "$ANDROID_BUILD_TOP" ]; then
+    echo "Run build/envsetup.sh first to set ANDROID_BUILD_TOP"
+    exit 1
+fi
+
+if ! $ADB_CMD wait-for-device shell pm path com.google.android.networkstack; then
+    echo "This device is already not using GMS modules"
+    exit 1
+fi
+
+read -p "This script is only for test purposes and highly likely to make your device unusable. \
+Continue ? <y/N>" prompt
+if [[ $prompt != "y" ]]
+then
+    exit 0
+fi
+
+cd $ANDROID_BUILD_TOP
+source build/envsetup.sh
+lunch aosp_arm64-trunk_staging-userdebug
+m NetworkStack CaptivePortalLogin com.android.tethering com.android.cellbroadcast \
+    com.android.resolv deapexer \
+    out/target/product/generic_arm64/system/etc/selinux/plat_mac_permissions.xml \
+    out/target/product/generic_arm64/system/etc/permissions/com.android.networkstack.xml
+
+$ADB_CMD root
+$ADB_CMD remount
+$ADB_CMD reboot
+
+echo "Waiting for boot..."
+$ADB_CMD wait-for-device;
+until [[ $($ADB_CMD shell getprop sys.boot_completed) == 1 ]]; do
+    sleep 1;
+done
+
+$ADB_CMD root
+$ADB_CMD remount
+
+push_apk priv-app NetworkStackGoogle NetworkStack
+push_apk app CaptivePortalLoginGoogle CaptivePortalLogin
+push_apex com.google.android.tethering com.android.tethering
+push_apex com.google.android.cellbroadcast com.android.cellbroadcast
+push_apex com.google.android.resolv com.android.resolv
+
+# Replace the network_stack key used to set its sepolicy context
+rm -f /tmp/pulled_plat_mac_permissions.xml
+$ADB_CMD pull /system/etc/selinux/plat_mac_permissions.xml /tmp/pulled_plat_mac_permissions.xml
+sed_replace='s/<signer signature="[0-9a-fA-F]+"><seinfo value="network_stack"\/><\/signer>/'$NETWORKSTACK_AOSP_SEPOLICY_KEY'/'
+sed -E "$sed_replace" /tmp/pulled_plat_mac_permissions.xml |
+    $ADB_CMD shell 'cat > /system/etc/selinux/plat_mac_permissions.xml'
+rm /tmp/pulled_plat_mac_permissions.xml
+
+# Update the networkstack privapp-permissions allowlist
+rm -f /tmp/pulled_privapp-permissions.xml
+$ADB_CMD pull /system/etc/permissions/privapp-permissions-google.xml /tmp/pulled_privapp-permissions.xml
+
+# Remove last </permission> line, and the permissions for com.google.android.networkstack
+sed -nE '1,/<\/permissions>/p' /tmp/pulled_privapp-permissions.xml \
+    | sed -E '/com.google.android.networkstack/,/privapp-permissions/d' > /tmp/modified_privapp-permissions.xml
+# Add the AOSP permissions and re-add the </permissions> line
+sed -nE '/com.android.networkstack/,/privapp-permissions/p' $ANDROID_PRODUCT_OUT/system/etc/permissions/com.android.networkstack.xml \
+    >> /tmp/modified_privapp-permissions.xml
+echo '</permissions>' >> /tmp/modified_privapp-permissions.xml
+
+$ADB_CMD push /tmp/modified_privapp-permissions.xml /system/etc/permissions/privapp-permissions-google.xml
+
+rm /tmp/pulled_privapp-permissions.xml /tmp/modified_privapp-permissions.xml
+
+echo "Done modifying, rebooting"
+$ADB_CMD reboot
\ No newline at end of file