diff --git a/packages/angular_devkit/build_angular/src/webpack/plugins/named-chunks-plugin.ts b/packages/angular_devkit/build_angular/src/webpack/plugins/named-chunks-plugin.ts
index feb0e5d208..3390682c5b 100644
--- a/packages/angular_devkit/build_angular/src/webpack/plugins/named-chunks-plugin.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/plugins/named-chunks-plugin.ts
@@ -41,6 +41,11 @@ export class NamedChunksPlugin {
         continue;
       }
 
+      if (block.groupOptions.name) {
+        // Ignore groups which have been named already.
+        return undefined;
+      }
+
       for (const dependency of block.dependencies) {
         if (dependency instanceof ImportDependency) {
           return Template.toPath(dependency.request);