diff --git a/packages/angular_devkit/build_angular/src/app-shell/index.ts b/packages/angular_devkit/build_angular/src/app-shell/index.ts
index 10c03cdb97eb..71dc853fec82 100644
--- a/packages/angular_devkit/build_angular/src/app-shell/index.ts
+++ b/packages/angular_devkit/build_angular/src/app-shell/index.ts
@@ -180,10 +180,9 @@ async function _appShellBuilder(
   let spinner: Spinner | undefined;
 
   try {
-    // Using `.result` instead of `.output` causes Webpack FS cache not to be created.
     const [browserResult, serverResult] = await Promise.all([
-      browserTargetRun.output.toPromise() as Promise<BrowserBuilderOutput>,
-      serverTargetRun.output.toPromise() as Promise<ServerBuilderOutput>,
+      browserTargetRun.result as Promise<BrowserBuilderOutput>,
+      serverTargetRun.result as Promise<ServerBuilderOutput>,
     ]);
 
     if (browserResult.success === false || browserResult.baseOutputPath === undefined) {
@@ -203,8 +202,7 @@ async function _appShellBuilder(
 
     return { success: false, error: err.message };
   } finally {
-    // workaround for [tsetse] All Promises in async functions must either be awaited or used in an expression.
-    const _ = Promise.all([browserTargetRun.stop(), serverTargetRun.stop()]);
+    await Promise.all([browserTargetRun.stop(), serverTargetRun.stop()]);
   }
 }
 
diff --git a/packages/angular_devkit/build_webpack/src/webpack/index.ts b/packages/angular_devkit/build_webpack/src/webpack/index.ts
index 8749e1237d0d..0dec67cb1fd6 100644
--- a/packages/angular_devkit/build_webpack/src/webpack/index.ts
+++ b/packages/angular_devkit/build_webpack/src/webpack/index.ts
@@ -72,16 +72,20 @@ export function runWebpack(
             log(stats, config);
 
             const statsOptions = typeof config.stats === 'boolean' ? undefined : config.stats;
-
-            obs.next({
+            const result = {
               success: !stats.hasErrors(),
               webpackStats: shouldProvideStats ? stats.toJson(statsOptions) : undefined,
               emittedFiles: getEmittedFiles(stats.compilation),
               outputPath: stats.compilation.outputOptions.path,
-            } as unknown as BuildResult);
+            } as unknown as BuildResult;
 
-            if (!config.watch) {
-              webpackCompiler.close(() => obs.complete());
+            if (config.watch) {
+              obs.next(result);
+            } else {
+              webpackCompiler.close(() => {
+                obs.next(result);
+                obs.complete();
+              });
             }
           };