diff --git a/.travis.yml b/.travis.yml
index d7a321d93..70b14ebe6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -84,6 +84,7 @@ jobs:
       cache:
         directories:
           - "$HOME/google-cloud-sdk/"
+          - "$HOME/.cache"
 
       before_install:
         - docker version
@@ -124,11 +125,19 @@ jobs:
           export CONDUIT_TAG=$(. bin/_tag.sh ; clean_head_root_tag)
           echo "CONDUIT_TAG=${CONDUIT_TAG}"
         - export BUILD_DEBUG=1 DOCKER_TRACE=1
+        - export DOCKER_CACHE="$HOME/.cache/docker.tgz" PROXY_BUILD_CACHE_IMAGE="proxy-build:cache"
+        - if [ -f "$DOCKER_CACHE" ]; then gunzip -c "$DOCKER_CACHE" | docker load ; docker image ls "$PROXY_BUILD_CACHE_IMAGE" ; fi
 
       script:
-        # We re-run the tests here in *release* (--release) mode since the
-        # `test` stage only runs them in *debug* mode.
+        - docker build . -f $rootdir/proxy/Dockerfile \
+            --build-arg="PROXY_UNOPTIMIZED=${PROXY_UNOPTIMIZED:-}" \
+            --cache-from="$PROXY_BUILD_CACHE_IMAGE" \
+            --tag "$PROXY_BUILD_CACHE_IMAGE" \
+            --target build
+        # bin/docker-build-proxy uses PROXY_BUILD_CACHE_IMAGE.
         - bin/docker-build
+        # The proxy's build cache is preserved so it can be reused on subsequent runs.
+        - docker save gcr.io/runconduit/proxy-build:cache | gzip -9 >"$DOCKER_CACHE"
 
       after_success:
         - bin/docker-push-deps
diff --git a/bin/docker-build-proxy b/bin/docker-build-proxy
index 6e8170384..65a051ed7 100755
--- a/bin/docker-build-proxy
+++ b/bin/docker-build-proxy
@@ -13,5 +13,14 @@ rootdir="$( cd $bindir/.. && pwd )"
 . $bindir/_docker.sh
 . $bindir/_tag.sh
 
-docker_build proxy "$(head_root_tag)" $rootdir/proxy/Dockerfile \
-    --build-arg="PROXY_UNOPTIMIZED=${PROXY_UNOPTIMIZED:-}"
+if [ -z "${PROXY_BUILD_CACHE_IMAGE:-}" ]; then
+    # If a cache is not specified use the default docker cache.
+    docker_build proxy "$(head_root_tag)" $rootdir/proxy/Dockerfile \
+        --build-arg="PROXY_UNOPTIMIZED=${PROXY_UNOPTIMIZED:-}"
+
+else
+    # Otherwise, if a cache image is specified, use it.
+    docker_build proxy "$(head_root_tag)" $rootdir/proxy/Dockerfile \
+        --build-arg="PROXY_UNOPTIMIZED=${PROXY_UNOPTIMIZED:-}" \
+        --cache-from="$PROXY_BUILD_CACHE_IMAGE"
+fi