diff --git a/packages/host/config/deploy.js b/packages/host/config/deploy.js
index f166dcdec4..712e353128 100644
--- a/packages/host/config/deploy.js
+++ b/packages/host/config/deploy.js
@@ -37,6 +37,12 @@ module.exports = function (deployTarget) {
     deployTarget === 's3-preview-production'
   ) {
     ENV.s3.prefix = process.env.PR_BRANCH_NAME;
+    // Previews should always serve the latest build for the PR, so a reviewer
+    // returning later sees current state without a shift-refresh. The default
+    // is `max-age=63072000, public` plus a 2029 Expires, which pins assets in
+    // the browser for ~2 years.
+    ENV.s3.cacheControl = 'no-cache, max-age=0, must-revalidate';
+    ENV.s3.expires = new Date(0);
   }
 
   return ENV;