diff --git a/.circleci/config.yml b/.circleci/config.yml
index 51bf53e037..3b1267df96 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -377,6 +377,10 @@ jobs:
 
   test_aio:
     executor: default-executor
+    parameters:
+      debugArtifactsDir:
+        type: string
+        default: aio/dist/size-debug-artifacts
     steps:
       - custom_attach_workspace
       - init_environment
@@ -395,6 +399,15 @@ jobs:
       - run: yarn --cwd aio test-a11y-score-localhost
         # Check the bundle sizes.
       - run: yarn --cwd aio payload-size
+        # When `payload-size` check fails, copy the files that were checked into `debugArtifactsDir`.
+      - run:
+          when: on_fail
+          name: Prepare JS bundles to be stored as artifacts
+          command: node aio/scripts/prepare-size-debug-artifacts aio << parameters.debugArtifactsDir >>
+        # Store files in `debugArtifactsDir` (if any) as artifacts for debugging purposes.
+      - store_artifacts:
+          path: << parameters.debugArtifactsDir >>
+          destination: aio
         # Run unit tests for Firebase redirects
       - run: yarn --cwd aio redirects-test
 
@@ -410,6 +423,9 @@ jobs:
 
   test_aio_local:
     parameters:
+      debugArtifactsDir:
+        type: string
+        default: aio/dist/size-debug-artifacts
       viewengine:
         type: boolean
         default: false
@@ -428,6 +444,15 @@ jobs:
       - run: yarn --cwd aio test-pwa-score-localhost $CI_AIO_MIN_PWA_SCORE
         # Check the bundle sizes.
       - run: yarn --cwd aio payload-size aio-local<<# parameters.viewengine >>-viewengine<</ parameters.viewengine >>
+        # When `payload-size` check fails, copy the files that were checked into `debugArtifactsDir`.
+      - run:
+          when: on_fail
+          name: Prepare JS bundles to be stored as artifacts
+          command: node aio/scripts/prepare-size-debug-artifacts aio-local<<# parameters.viewengine >>-viewengine<</ parameters.viewengine >> << parameters.debugArtifactsDir >>
+        # Store files in `debugArtifactsDir` (if any) as artifacts for debugging purposes.
+      - store_artifacts:
+          path: << parameters.debugArtifactsDir >>
+          destination: aio
 
   test_aio_tools:
     executor: default-executor
diff --git a/aio/scripts/prepare-size-debug-artifacts.js b/aio/scripts/prepare-size-debug-artifacts.js
new file mode 100644
index 0000000000..503948baa2
--- /dev/null
+++ b/aio/scripts/prepare-size-debug-artifacts.js
@@ -0,0 +1,24 @@
+#!/usr/bin/env node
+const {cp, ls, mkdir, set} = require('shelljs');
+const {join, resolve} = require('path');
+set('-e');
+
+// Read input arguments.
+const [sizesTarget, artifactsRelativeDir] = process.argv.slice(2);
+
+// Compute paths.
+const projectDir = resolve(__dirname, '../..');
+const sizesFilePath = join(projectDir, 'goldens/size-tracking/aio-payloads.json');
+const distDir = join(projectDir, 'aio/dist');
+const artifactsDir = resolve(projectDir, artifactsRelativeDir);
+
+// Determine which files need to be copied.
+const fileNamePrefixes = Object.keys(require(sizesFilePath)[sizesTarget].master.uncompressed);
+const filesToCopyRe = new RegExp(`^(?:${fileNamePrefixes.join('|')})\\..+\\.js$`);
+const filesToCopy = ls(distDir)
+    .filter(file => filesToCopyRe.test(file))
+    .map(file => join(distDir, file));
+
+// Copy files to the specified directory.
+mkdir('-p', artifactsDir);
+cp(filesToCopy, artifactsDir);