diff --git a/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts b/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
index 00b057b3e7..ce9900194f 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
@@ -48,8 +48,8 @@ export class CachedFileSystem implements FileSystem {
     }
   }
 
-  writeFile(path: AbsoluteFsPath, data: string): void {
-    this.delegate.writeFile(path, data);
+  writeFile(path: AbsoluteFsPath, data: string, exclusive?: boolean): void {
+    this.delegate.writeFile(path, data, exclusive);
     this.readFileCache.set(path, data);
     this.existsCache.set(path, true);
   }
diff --git a/packages/compiler-cli/src/ngtsc/file_system/src/invalid_file_system.ts b/packages/compiler-cli/src/ngtsc/file_system/src/invalid_file_system.ts
index 11b2c8ab15..693f813af4 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/src/invalid_file_system.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/src/invalid_file_system.ts
@@ -18,7 +18,7 @@ import {AbsoluteFsPath, FileStats, FileSystem, PathSegment, PathString} from './
 export class InvalidFileSystem implements FileSystem {
   exists(path: AbsoluteFsPath): boolean { throw makeError(); }
   readFile(path: AbsoluteFsPath): string { throw makeError(); }
-  writeFile(path: AbsoluteFsPath, data: string): void { throw makeError(); }
+  writeFile(path: AbsoluteFsPath, data: string, exclusive?: boolean): void { throw makeError(); }
   removeFile(path: AbsoluteFsPath): void { throw makeError(); }
   symlink(target: AbsoluteFsPath, path: AbsoluteFsPath): void { throw makeError(); }
   readdir(path: AbsoluteFsPath): PathSegment[] { throw makeError(); }
diff --git a/packages/compiler-cli/src/ngtsc/file_system/src/node_js_file_system.ts b/packages/compiler-cli/src/ngtsc/file_system/src/node_js_file_system.ts
index 9670504d6a..042c827dfd 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/src/node_js_file_system.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/src/node_js_file_system.ts
@@ -18,7 +18,9 @@ export class NodeJSFileSystem implements FileSystem {
   private _caseSensitive: boolean|undefined = undefined;
   exists(path: AbsoluteFsPath): boolean { return fs.existsSync(path); }
   readFile(path: AbsoluteFsPath): string { return fs.readFileSync(path, 'utf8'); }
-  writeFile(path: AbsoluteFsPath, data: string): void { fs.writeFileSync(path, data, 'utf8'); }
+  writeFile(path: AbsoluteFsPath, data: string, exclusive: boolean = false): void {
+    fs.writeFileSync(path, data, exclusive ? {flag: 'wx'} : undefined);
+  }
   removeFile(path: AbsoluteFsPath): void { fs.unlinkSync(path); }
   symlink(target: AbsoluteFsPath, path: AbsoluteFsPath): void { fs.symlinkSync(target, path); }
   readdir(path: AbsoluteFsPath): PathSegment[] { return fs.readdirSync(path) as PathSegment[]; }
diff --git a/packages/compiler-cli/src/ngtsc/file_system/src/types.ts b/packages/compiler-cli/src/ngtsc/file_system/src/types.ts
index eb3410d032..28f5defa84 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/src/types.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/src/types.ts
@@ -37,7 +37,7 @@ export type PathSegment = BrandedPath<'PathSegment'>;
 export interface FileSystem {
   exists(path: AbsoluteFsPath): boolean;
   readFile(path: AbsoluteFsPath): string;
-  writeFile(path: AbsoluteFsPath, data: string): void;
+  writeFile(path: AbsoluteFsPath, data: string, exclusive?: boolean): void;
   removeFile(path: AbsoluteFsPath): void;
   symlink(target: AbsoluteFsPath, path: AbsoluteFsPath): void;
   readdir(path: AbsoluteFsPath): PathSegment[];
diff --git a/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts b/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
index 401b9f1bdf..354373940d 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
@@ -94,7 +94,10 @@ describe('CachedFileSystem', () => {
     it('should call delegate', () => {
       const spy = spyOn(delegate, 'writeFile');
       fs.writeFile(abcPath, 'Some contents');
-      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents');
+      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents', undefined);
+      spy.calls.reset();
+      fs.writeFile(abcPath, 'Some contents', /* exclusive */ true);
+      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents', true);
     });
 
     it('should update the exists and "readFile" caches', () => {
diff --git a/packages/compiler-cli/src/ngtsc/file_system/test/node_js_file_system_spec.ts b/packages/compiler-cli/src/ngtsc/file_system/test/node_js_file_system_spec.ts
index c4f5161c3d..d17af51223 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/test/node_js_file_system_spec.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/test/node_js_file_system_spec.ts
@@ -47,7 +47,10 @@ describe('NodeJSFileSystem', () => {
     it('should delegate to fs.writeFileSync()', () => {
       const spy = spyOn(realFs, 'writeFileSync');
       fs.writeFile(abcPath, 'Some contents');
-      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents', 'utf8');
+      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents', undefined);
+      spy.calls.reset();
+      fs.writeFile(abcPath, 'Some contents', /* exclusive */ true);
+      expect(spy).toHaveBeenCalledWith(abcPath, 'Some contents', {flag: 'wx'});
     });
   });
 
diff --git a/packages/compiler-cli/src/ngtsc/file_system/testing/src/mock_file_system.ts b/packages/compiler-cli/src/ngtsc/file_system/testing/src/mock_file_system.ts
index d8bae1db87..7dcd81249d 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/testing/src/mock_file_system.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/testing/src/mock_file_system.ts
@@ -34,13 +34,17 @@ export abstract class MockFileSystem implements FileSystem {
     }
   }
 
-  writeFile(path: AbsoluteFsPath, data: string): void {
+  writeFile(path: AbsoluteFsPath, data: string, exclusive: boolean = false): void {
     const [folderPath, basename] = this.splitIntoFolderAndFile(path);
     const {entity} = this.findFromPath(folderPath);
     if (entity === null || !isFolder(entity)) {
       throw new MockFileSystemError(
           'ENOENT', path, `Unable to write file "${path}". The containing folder does not exist.`);
     }
+    if (exclusive && entity[basename] !== undefined) {
+      throw new MockFileSystemError(
+          'EEXIST', path, `Unable to exclusively write file "${path}". The file already exists.`);
+    }
     entity[basename] = data;
   }