diff --git a/.travis.yml b/.travis.yml
index 99d119366..8ad21aaf5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -144,7 +144,7 @@ matrix:
         # This command should be kept in sync with ray/python/README-building-wheels.md,
         # except the `$MOUNT_BAZEL_CACHE` part.
 
-        - ./ci/suppress_output docker run --rm -w /ray -v `pwd`:/ray $MOUNT_BAZEL_CACHE -ti rayproject/arrow_linux_x86_64_base:ARROW-5631 /ray/python/build-wheel-manylinux1.sh
+        - ./ci/suppress_output docker run -e TRAVIS_COMMIT=$TRAVIS_COMMIT --rm -w /ray -v `pwd`:/ray $MOUNT_BAZEL_CACHE -ti rayproject/arrow_linux_x86_64_base:ARROW-5631 /ray/python/build-wheel-manylinux1.sh
 
       script:
         - if [ $RAY_CI_LINUX_WHEELS_AFFECTED != "1" ]; then exit; fi
diff --git a/ci/travis/test-wheels.sh b/ci/travis/test-wheels.sh
index 3314f221a..e9e3e258d 100755
--- a/ci/travis/test-wheels.sh
+++ b/ci/travis/test-wheels.sh
@@ -40,6 +40,9 @@ if [[ "$platform" == "linux" ]]; then
   # Install the wheel.
   $PIP_CMD install -q "$PYTHON_WHEEL"
 
+  # Check that ray.__commit__ was set properly.
+  $PYTHON_EXE -u -c "import ray; print(ray.__commit__)" | grep $TRAVIS_COMMIT || (echo "ray.__commit__ not set properly!" && exit 1)
+
   # Run a simple test script to make sure that the wheel works.
   INSTALLED_RAY_DIRECTORY=$(dirname "$($PYTHON_EXE -u -c "import ray; print(ray.__file__)" | tail -n1)")
   $PYTHON_EXE "$TEST_SCRIPT"
diff --git a/python/build-wheel-macos.sh b/python/build-wheel-macos.sh
index 74e9ca79c..7960866b7 100755
--- a/python/build-wheel-macos.sh
+++ b/python/build-wheel-macos.sh
@@ -79,6 +79,13 @@ for ((i=0; i<${#PY_VERSIONS[@]}; ++i)); do
     $PIP_CMD install -q numpy==$NUMPY_VERSION cython==0.29.0
     # Install wheel to avoid the error "invalid command 'bdist_wheel'".
     $PIP_CMD install -q wheel
+    # Set the commit SHA in __init__.py.
+    if [ -n "$TRAVIS_COMMIT" ]; then
+      sed -i.bak "s/{{RAY_COMMIT_SHA}}/$TRAVIS_COMMIT/g" ray/__init__.py && rm ray/__init__.py.bak
+    else
+      echo "TRAVIS_COMMIT variable not set - required to populated ray.__commit__."
+      exit 1
+    fi
     # Add the correct Python to the path and build the wheel. This is only
     # needed so that the installation finds the cython executable.
     PATH=$MACPYTHON_PY_PREFIX/$PY_MM/bin:$PATH $PYTHON_EXE setup.py bdist_wheel
diff --git a/python/build-wheel-manylinux1.sh b/python/build-wheel-manylinux1.sh
index 04aecf135..ea4926c77 100755
--- a/python/build-wheel-manylinux1.sh
+++ b/python/build-wheel-manylinux1.sh
@@ -28,6 +28,7 @@ sudo apt-get install unzip
 export PATH=$PATH:/root/bin
 
 # Install and use the latest version of Node.js in order to build the dashboard.
+set +x
 curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.34.0/install.sh | bash
 source $HOME/.nvm/nvm.sh
 nvm install node
@@ -38,6 +39,7 @@ pushd python/ray/dashboard/client
   npm ci
   npm run build
 popd
+set -x
 
 mkdir .whl
 for ((i=0; i<${#PYTHONS[@]}; ++i)); do
@@ -54,6 +56,14 @@ for ((i=0; i<${#PYTHONS[@]}; ++i)); do
     # Fix the numpy version because this will be the oldest numpy version we can
     # support.
     /opt/python/${PYTHON}/bin/pip install -q numpy==${NUMPY_VERSION} cython==0.29.0
+    # Set the commit SHA in __init__.py.
+    if [ -n "$TRAVIS_COMMIT" ]; then
+      sed -i.bak "s/{{RAY_COMMIT_SHA}}/$TRAVIS_COMMIT/g" ray/__init__.py && rm ray/__init__.py.bak
+    else
+      echo "TRAVIS_COMMIT variable not set - required to populated ray.__commit__."
+      exit 1
+    fi
+
     PATH=/opt/python/${PYTHON}/bin:$PATH /opt/python/${PYTHON}/bin/python setup.py bdist_wheel
     # In the future, run auditwheel here.
     mv dist/*.whl ../.whl/
diff --git a/python/ray/__init__.py b/python/ray/__init__.py
index 9874d36c2..d813f226e 100644
--- a/python/ray/__init__.py
+++ b/python/ray/__init__.py
@@ -98,7 +98,8 @@ from ray.runtime_context import _get_runtime_context  # noqa: E402
 from ray.cross_language import java_function, java_actor_class  # noqa: E402
 from ray import util  # noqa: E402
 
-# Ray version string.
+# Replaced with the current commit when building the wheels.
+__commit__ = "{{RAY_COMMIT_SHA}}"
 __version__ = "0.9.0.dev0"
 
 __all__ = [