diff --git a/docker/Dockerfile.builder b/docker/Dockerfile.builder
index ee21b22356..b9b1ac3538 100644
--- a/docker/Dockerfile.builder
+++ b/docker/Dockerfile.builder
@@ -1,27 +1,27 @@
+# syntax=docker/dockerfile:1.7-labs
+
 # Target with dependencies to build all flow tools from their sources.
 # i.e., "./build_openroad.sh --local" from inside a docker container
 # NOTE: don't use this file directly unless you know what you are doing,
 # instead use etc/DockerHelper.sh
+
 ARG fromImage=openroad/flow-ubuntu22.04-dev:latest
 
 FROM $fromImage AS openroad-builder-base
-
 ARG numThreads=$(nproc)
 
-COPY . /OpenROAD-flow-scripts
 WORKDIR /OpenROAD-flow-scripts
-
+COPY --link dev_env.sh dev_env.sh
+COPY --link build_openroad.sh build_openroad.sh
+COPY --parents .git/modules tools ./
 RUN ./build_openroad.sh --no_init --local --threads ${numThreads}
 
-FROM $fromImage AS openroad-flow-scripts-base
-
-COPY . /OpenROAD-flow-scripts
-
-RUN rm -rf /OpenROAD-flow-scripts/tools /OpenROAD-flow-scripts/.git
+FROM $fromImage AS openroad-flow-scripts-merged
 
-COPY --from=openroad-builder-base /OpenROAD-flow-scripts/tools/install /OpenROAD-flow-scripts/tools/install
+COPY --link --exclude=.git* --exclude=tools/ . /OpenROAD-flow-scripts/
+COPY --link --from=openroad-builder-base /OpenROAD-flow-scripts/tools/install /OpenROAD-flow-scripts/tools/install/
 
 FROM $fromImage
 
-COPY --from=openroad-flow-scripts-base /OpenROAD-flow-scripts /OpenROAD-flow-scripts
+COPY --from=openroad-flow-scripts-merged /OpenROAD-flow-scripts /OpenROAD-flow-scripts
 WORKDIR /OpenROAD-flow-scripts