diff --git a/live-build/build-livefs-lxd b/live-build/build-livefs-lxd
index 608e1f9b..5d43670e 100755
--- a/live-build/build-livefs-lxd
+++ b/live-build/build-livefs-lxd
@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+import configparser
 import pathlib
 import subprocess
 import time
@@ -7,6 +8,15 @@ import time
 import click
 
 
+_CONFIG_FILE = pathlib.Path.home() / ".config" / "livecd-rootfs" / "build-livefs.conf"
+
+
+def _read_config() -> dict[str, str]:
+    cp = configparser.ConfigParser()
+    cp.read(_CONFIG_FILE)
+    return dict(cp["defaults"]) if "defaults" in cp else {}
+
+
 @click.command(
     context_settings={"ignore_unknown_options": True, "allow_extra_args": True}
 )
@@ -16,25 +26,39 @@ import click
     default=None,
     help="LXD VM name (default: livefs-builder-{suite})",
 )
+@click.option(
+    "--http-proxy",
+    default=None,
+    help="HTTP proxy URL for apt inside the VM (also read from build-livefs.conf)",
+)
 @click.argument("extra_args", nargs=-1, type=click.UNPROCESSED)
-def main(suite, vm_name, extra_args):
+def main(suite, vm_name, http_proxy, extra_args):
     livecd_rootfs_root = pathlib.Path(__file__).resolve().parent.parent
     vm_name = vm_name or f"livefs-builder-{suite}"
     host_conf = (
         pathlib.Path.home() / ".config" / "livecd-rootfs" / "build-livefs.conf"
     )
 
+    if http_proxy is None:
+        http_proxy = _read_config().get("http-proxy")
+
     result = subprocess.run(["lxc", "info", vm_name], capture_output=True)
     if result.returncode != 0:
-        subprocess.run(
-            [
-                "lxc", "launch", f"ubuntu-daily:{suite}", vm_name, "--vm",
-                "--config", "limits.cpu=4",
-                "--config", "limits.memory=8GiB",
-                "--device", "root,size=100GiB",
-            ],
-            check=True,
-        )
+        launch_cmd = [
+            "lxc", "launch", f"ubuntu-daily:{suite}", vm_name, "--vm",
+            "--config", "limits.cpu=4",
+            "--config", "limits.memory=8GiB",
+            "--device", "root,size=100GiB",
+        ]
+        user_data = "#cloud-config\npackage_update: true\n"
+        if http_proxy is not None:
+            user_data += (
+                "apt:\n"
+                f"  http_proxy: {http_proxy}\n"
+                f"  https_proxy: {http_proxy}\n"
+            )
+        launch_cmd += ["--config", f"user.user-data={user_data}"]
+        subprocess.run(launch_cmd, check=True)
 
     device_info = subprocess.run(
         ["lxc", "config", "device", "show", vm_name],