diff --git a/tools/jenkins/build_and_run_docker.sh b/tools/jenkins/build_and_run_docker.sh
index 448b00c0..18b910a7 100755
--- a/tools/jenkins/build_and_run_docker.sh
+++ b/tools/jenkins/build_and_run_docker.sh
@@ -46,16 +46,18 @@ cd -
 # Use image name based on Dockerfile location checksum
 DOCKER_IMAGE_NAME=$(basename $DOCKERFILE_DIR)_$(sha1sum $DOCKERFILE_DIR/Dockerfile | cut -f1 -d\ )
 
-# Make sure docker image has been built. Should be instantaneous if so.
-docker build -t $DOCKER_IMAGE_NAME $DOCKERFILE_DIR
-
-# Choose random name for docker container
-CONTAINER_NAME="build_and_run_docker_$(uuidgen)"
-
 # Ensure existence of ccache directory
 CCACHE_DIR=/tmp/protobuf-ccache
 mkdir -p $CCACHE_DIR
 
+# Make sure docker image has been built. Should be instantaneous if so.
+docker build \
+  -v $CCACHE_DIR:$CCACHE_DIR \
+  -t $DOCKER_IMAGE_NAME $DOCKERFILE_DIR
+
+# Choose random name for docker container
+CONTAINER_NAME="build_and_run_docker_$(uuidgen)"
+
 # Run command inside docker
 docker run \
   "$@" \
diff --git a/tools/jenkins/make_test_output.py b/tools/jenkins/make_test_output.py
index 0ba5db3b..986d1979 100644
--- a/tools/jenkins/make_test_output.py
+++ b/tools/jenkins/make_test_output.py
@@ -58,8 +58,8 @@ def readtests(basedir):
   # up in the job log.
   tests["cpp"]["name"] = "cpp"
 
-  # TODO
-  tests["cpp"]["time"] = "0"
+  with open(basedir + '/logs/1/cpp/build_time', 'r') as f:
+    tests["cpp"]["time"] = f.read().strip()
   tests["cpp"]["failure"] = False
 
   ret = tests.values()
diff --git a/tools/run_tests/jenkins.sh b/tools/run_tests/jenkins.sh
index 32050d25..0bd9ffe5 100755
--- a/tools/run_tests/jenkins.sh
+++ b/tools/run_tests/jenkins.sh
@@ -34,7 +34,12 @@ mkdir -p $LOG_OUTPUT_DIR/1/cpp
 #  $DIR/logs/1/java_jdk7/stderr
 CPP_STDOUT=$LOG_OUTPUT_DIR/1/cpp/stdout
 CPP_STDERR=$LOG_OUTPUT_DIR/1/cpp/stderr
-$TEST_SCRIPT cpp > >(tee $CPP_STDOUT) 2> >(tee $CPP_STDERR >&2)
+
+# It's important that we get /usr/bin/time (which supports -f and -o) and not
+# the bash builtin "time" which doesn't.
+TIME_CMD="/usr/bin/time -f %e -o $LOG_OUTPUT_DIR/1/cpp/build_time"
+
+$TIME_CMD $TEST_SCRIPT cpp > >(tee $CPP_STDOUT) 2> >(tee $CPP_STDERR >&2)
 
 # Other tests are run in parallel.  The overall run fails if any one of them
 # fails.