diff --git a/.circleci/config.yml b/.circleci/config.yml
index 366993a030..ead922855a 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -120,19 +120,25 @@ commands:
       - attach_workspace:
           at: *workspace_location
 
+  # Overwrite the yarn installed in the docker container with our own version.
+  overwrite_yarn:
+    description: Overwrite yarn with our own version
+    steps:
+      - run:
+          name: Overwrite yarn
+          command: |
+            localYarnPath=`node ./.circleci/get-vendored-yarn-path.js`
+            sudo chmod a+x $localYarnPath
+            sudo ln -fs $localYarnPath /usr/local/bin/yarn
+      - run: node --version
+      - run: yarn --version
+
   # Initializes the CI environment by setting up common environment variables.
   init_environment:
     description: Initializing environment (setting up variables, overwriting Yarn)
     steps:
       - run: ./.circleci/env.sh
-      - run:
-          # Overwrite the yarn installed in the docker container with our own version.
-          name: Overwrite yarn with our own version
-          command: |
-            sudo chmod a+x $CI_LOCAL_YARN_PATH
-            sudo ln -fs $CI_LOCAL_YARN_PATH /usr/local/bin/yarn
-      - run: node --version
-      - run: yarn --version
+      - overwrite_yarn
       - run:
           # Configure git as the CircleCI `checkout` command does.
           # This is needed because we only checkout on the setup job.
@@ -657,10 +663,16 @@ jobs:
       - init_environment
       - run: setPublicVar_CI_STABLE_BRANCH
       - run:
-          name: Check out `aio/` from the stable branch
+          name: Check out `aio/` and `third_party/github.com/yarnpkg/` from the stable branch
           command: |
+            localYarnDir=third_party/github.com/yarnpkg/
+            # Remove the directory to ensure there will be only one version available (the one
+            # checked out from the stable branch below).
+            rm -rf $localYarnDir
             git fetch origin $CI_STABLE_BRANCH
-            git checkout --force origin/$CI_STABLE_BRANCH -- aio/
+            git checkout --force origin/$CI_STABLE_BRANCH -- aio/ $localYarnDir
+        # Overwrite yarn again to use the version from the checked out branch.
+      - overwrite_yarn
       - run:
           name: Run tests against https://angular.io/
           command: ./aio/scripts/test-production.sh https://angular.io/ $CI_AIO_MIN_PWA_SCORE
diff --git a/.circleci/env.sh b/.circleci/env.sh
index c5f9fcbc86..f9734fbfa5 100755
--- a/.circleci/env.sh
+++ b/.circleci/env.sh
@@ -35,7 +35,6 @@ setPublicVar CI_COMMIT_RANGE "`[[ ${CIRCLE_PR_NUMBER:-false} != false ]] && echo
 setPublicVar CI_PULL_REQUEST "${CIRCLE_PR_NUMBER:-false}";
 setPublicVar CI_REPO_NAME "$CIRCLE_PROJECT_REPONAME";
 setPublicVar CI_REPO_OWNER "$CIRCLE_PROJECT_USERNAME";
-setPublicVar CI_LOCAL_YARN_PATH "`node $projectDir/.circleci/get-vendored-yarn-path.js`";
 
 
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