diff --git a/packages/core/schematics/migrations/missing-injectable/providers_evaluator.ts b/packages/core/schematics/migrations/missing-injectable/providers_evaluator.ts
index c3fd96ae47..8399fc8360 100644
--- a/packages/core/schematics/migrations/missing-injectable/providers_evaluator.ts
+++ b/packages/core/schematics/migrations/missing-injectable/providers_evaluator.ts
@@ -28,7 +28,7 @@ export interface ProviderLiteral {
 export class ProvidersEvaluator extends StaticInterpreter {
   private _providerLiterals: ProviderLiteral[] = [];
 
-  visitObjectLiteralExpression(node: ts.ObjectLiteralExpression, context: any) {
+  override visitObjectLiteralExpression(node: ts.ObjectLiteralExpression, context: any) {
     const resolvedValue =
         super.visitObjectLiteralExpression(node, {...context, insideProviderDef: true});
     // do not collect nested object literals. e.g. a provider could use a
diff --git a/packages/core/schematics/migrations/static-queries/strategies/usage_strategy/template_usage_visitor.ts b/packages/core/schematics/migrations/static-queries/strategies/usage_strategy/template_usage_visitor.ts
index 0d174244fa..136cc957aa 100644
--- a/packages/core/schematics/migrations/static-queries/strategies/usage_strategy/template_usage_visitor.ts
+++ b/packages/core/schematics/migrations/static-queries/strategies/usage_strategy/template_usage_visitor.ts
@@ -32,7 +32,7 @@ export class TemplateUsageVisitor extends NullVisitor {
     return !this.hasQueryTemplateReference && this.expressionAstVisitor.hasQueryPropertyRead;
   }
 
-  visitElement(element: Element): void {
+  override visitElement(element: Element): void {
     // In case there is a template references variable that matches the query property
     // name, we can finish this visitor as such a template variable can be used in the
     // entire template and the query therefore can't be accessed from the template.
@@ -47,7 +47,7 @@ export class TemplateUsageVisitor extends NullVisitor {
     visitAll(this, element.children);
   }
 
-  visitTemplate(template: Template): void {
+  override visitTemplate(template: Template): void {
     visitAll(this, template.attributes);
     visitAll(this, template.inputs);
     visitAll(this, template.outputs);
@@ -57,15 +57,15 @@ export class TemplateUsageVisitor extends NullVisitor {
     // lifecycle hook at the earliest.
   }
 
-  visitBoundAttribute(attribute: BoundAttribute) {
+  override visitBoundAttribute(attribute: BoundAttribute) {
     attribute.value.visit(this.expressionAstVisitor, attribute.sourceSpan);
   }
 
-  visitBoundText(text: BoundText) {
+  override visitBoundText(text: BoundText) {
     text.value.visit(this.expressionAstVisitor, text.sourceSpan);
   }
 
-  visitBoundEvent(node: BoundEvent) {
+  override visitBoundEvent(node: BoundEvent) {
     node.handler.visit(this.expressionAstVisitor, node.handlerSpan);
   }
 }
@@ -81,7 +81,7 @@ class ExpressionAstVisitor extends RecursiveAstVisitor {
     super();
   }
 
-  visitPropertyRead(node: PropertyRead, span: ParseSourceSpan): any {
+  override visitPropertyRead(node: PropertyRead, span: ParseSourceSpan): any {
     // The receiver of the property read needs to be "implicit" as queries are accessed
     // from the component instance and not from other objects.
     if (node.receiver instanceof ImplicitReceiver && node.name === this.queryPropertyName) {
diff --git a/packages/core/schematics/migrations/template-var-assignment/angular/html_variable_assignment_visitor.ts b/packages/core/schematics/migrations/template-var-assignment/angular/html_variable_assignment_visitor.ts
index faa2193985..719c87ca08 100644
--- a/packages/core/schematics/migrations/template-var-assignment/angular/html_variable_assignment_visitor.ts
+++ b/packages/core/schematics/migrations/template-var-assignment/angular/html_variable_assignment_visitor.ts
@@ -26,12 +26,12 @@ export class HtmlVariableAssignmentVisitor extends NullVisitor {
   private expressionAstVisitor =
       new ExpressionAstVisitor(this.variableAssignments, this.currentVariables);
 
-  visitElement(element: Element): void {
+  override visitElement(element: Element): void {
     visitAll(this, element.outputs);
     visitAll(this, element.children);
   }
 
-  visitTemplate(template: Template): void {
+  override visitTemplate(template: Template): void {
     // Keep track of the template variables which can be accessed by the template
     // child nodes through the implicit receiver.
     this.currentVariables.push(...template.variables);
@@ -52,7 +52,7 @@ export class HtmlVariableAssignmentVisitor extends NullVisitor {
     });
   }
 
-  visitBoundEvent(node: BoundEvent) {
+  override visitBoundEvent(node: BoundEvent) {
     node.handler.visit(this.expressionAstVisitor, node.handlerSpan);
   }
 }
@@ -65,7 +65,7 @@ class ExpressionAstVisitor extends RecursiveAstVisitor {
     super();
   }
 
-  visitPropertyWrite(node: PropertyWrite, span: ParseSourceSpan) {
+  override visitPropertyWrite(node: PropertyWrite, span: ParseSourceSpan) {
     if (node.receiver instanceof ImplicitReceiver &&
         this.currentVariables.some(v => v.name === node.name)) {
       this.variableAssignments.push({
diff --git a/packages/core/src/compiler/compiler_facade_interface.ts b/packages/core/src/compiler/compiler_facade_interface.ts
index 3bfb7d2fc1..14ac1a341b 100644
--- a/packages/core/src/compiler/compiler_facade_interface.ts
+++ b/packages/core/src/compiler/compiler_facade_interface.ts
@@ -63,7 +63,9 @@ export interface CompilerFacade {
   createParseSourceSpan(kind: string, typeName: string, sourceUrl: string): ParseSourceSpan;
 
   FactoryTarget: typeof FactoryTarget;
-  ResourceLoader: {new(): ResourceLoader};
+  // Note that we do not use `{new(): ResourceLoader}` here because
+  // the resource loader class is abstract and not constructable.
+  ResourceLoader: Function&{prototype: ResourceLoader};
 }
 
 export interface CoreEnvironment {
diff --git a/packages/core/src/event_emitter.ts b/packages/core/src/event_emitter.ts
index 3136af5f9e..a7eea17c14 100644
--- a/packages/core/src/event_emitter.ts
+++ b/packages/core/src/event_emitter.ts
@@ -114,7 +114,7 @@ class EventEmitter_ extends Subject<any> {
     super.next(value);
   }
 
-  subscribe(observerOrNext?: any, error?: any, complete?: any): Subscription {
+  override subscribe(observerOrNext?: any, error?: any, complete?: any): Subscription {
     let nextFn = observerOrNext;
     let errorFn = error || (() => null);
     let completeFn = complete;
diff --git a/packages/core/src/render3/view_ref.ts b/packages/core/src/render3/view_ref.ts
index c7026fb06f..69d171c8b3 100644
--- a/packages/core/src/render3/view_ref.ts
+++ b/packages/core/src/render3/view_ref.ts
@@ -308,15 +308,15 @@ export class RootViewRef<T> extends ViewRef<T> {
     super(_view);
   }
 
-  detectChanges(): void {
+  override detectChanges(): void {
     detectChangesInRootView(this._view);
   }
 
-  checkNoChanges(): void {
+  override checkNoChanges(): void {
     checkNoChangesInRootView(this._view);
   }
 
-  get context(): T {
+  override get context(): T {
     return null!;
   }
 }
diff --git a/packages/core/test/acceptance/change_detection_spec.ts b/packages/core/test/acceptance/change_detection_spec.ts
index 36b07659ed..a360a5b581 100644
--- a/packages/core/test/acceptance/change_detection_spec.ts
+++ b/packages/core/test/acceptance/change_detection_spec.ts
@@ -1189,7 +1189,7 @@ describe('change detection', () => {
       // Custom error handler that just rethrows all the errors from the
       // view, rather than logging them out. Used to keep our logs clean.
       class RethrowErrorHandler extends ErrorHandler {
-        handleError(error: any) {
+        override handleError(error: any) {
           throw error;
         }
       }
diff --git a/packages/core/test/acceptance/change_detection_transplanted_view_spec.ts b/packages/core/test/acceptance/change_detection_transplanted_view_spec.ts
index 815aebcb5c..235e6933da 100644
--- a/packages/core/test/acceptance/change_detection_transplanted_view_spec.ts
+++ b/packages/core/test/acceptance/change_detection_transplanted_view_spec.ts
@@ -54,11 +54,11 @@ describe('change detection for transplanted views', () => {
       template: insertCompTemplate,
     })
     class InsertForOnPushDeclareComp extends InsertComp {
-      constructor(public changeDetectorRef: ChangeDetectorRef) {
+      constructor(changeDetectorRef: ChangeDetectorRef) {
         super(changeDetectorRef);
         insertForOnPushDeclareComp = this;
       }
-      get template(): TemplateRef<any> {
+      override get template(): TemplateRef<any> {
         return onPushDeclareComp.myTmpl;
       }
     }
@@ -105,7 +105,7 @@ describe('change detection for transplanted views', () => {
       changeDetection: ChangeDetectionStrategy.OnPush
     })
     class OnPushDeclareComp extends DeclareComp {
-      constructor(readonly changeDetector: ChangeDetectorRef) {
+      constructor(changeDetector: ChangeDetectorRef) {
         super(changeDetector);
         onPushDeclareComp = this;
       }
diff --git a/packages/core/test/acceptance/copy_definition_feature_spec.ts b/packages/core/test/acceptance/copy_definition_feature_spec.ts
index 36bfa2d0de..35a74ae42f 100644
--- a/packages/core/test/acceptance/copy_definition_feature_spec.ts
+++ b/packages/core/test/acceptance/copy_definition_feature_spec.ts
@@ -40,7 +40,7 @@ describe('Ivy CopyDefinitionFeature', () => {
             }
 
             class ChildComponent extends BaseComponent {
-              static ɵcmp = defineComponent({
+              static override ɵcmp = defineComponent({
                 type: ChildComponent,
                 selectors: [['some-cmp']],
                 features: [InheritDefinitionFeature, CopyDefinitionFeature],
@@ -49,7 +49,7 @@ describe('Ivy CopyDefinitionFeature', () => {
                 template: function ChildComponent_Template(rf, ctx) {},
                 encapsulation: 2
               });
-              static ɵfac = function ChildComponent_Factory(t: any) {
+              static override ɵfac = function ChildComponent_Factory(t: any) {
                 return new (t || ChildComponent)();
               };
             }
diff --git a/packages/core/test/acceptance/di_spec.ts b/packages/core/test/acceptance/di_spec.ts
index 69cda5ce1b..7c1001e48a 100644
--- a/packages/core/test/acceptance/di_spec.ts
+++ b/packages/core/test/acceptance/di_spec.ts
@@ -2040,7 +2040,7 @@ describe('di', () => {
       }
 
       class MyRootService extends MyService {
-        id = 2;
+        override id = 2;
       }
 
       @Component({template: ''})
diff --git a/packages/core/test/acceptance/inherit_definition_feature_spec.ts b/packages/core/test/acceptance/inherit_definition_feature_spec.ts
index 876fc4c23f..6a36e60771 100644
--- a/packages/core/test/acceptance/inherit_definition_feature_spec.ts
+++ b/packages/core/test/acceptance/inherit_definition_feature_spec.ts
@@ -321,7 +321,7 @@ describe('inheritance', () => {
       }
 
       abstract class UndecoratedBase extends Base {
-        abstract input: any;
+        abstract override input: any;
         ngOnChanges() {
           changes++;
         }
@@ -383,7 +383,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -424,7 +424,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -465,7 +465,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -506,7 +506,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -547,7 +547,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -588,7 +588,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -629,7 +629,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -684,7 +684,7 @@ describe('inheritance', () => {
           selector: '[sub-dir]',
         })
         class SubDirective extends SuperDirective {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -943,7 +943,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -984,7 +984,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -1025,7 +1025,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -1066,7 +1066,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -1107,7 +1107,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -1148,7 +1148,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -1189,7 +1189,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -1245,7 +1245,7 @@ describe('inheritance', () => {
           selector: '[sub-dir]',
         })
         class SubDirective extends SuperDirective {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -1513,7 +1513,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -1554,7 +1554,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -1595,7 +1595,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -1636,7 +1636,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -1677,7 +1677,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -1718,7 +1718,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -1759,7 +1759,7 @@ describe('inheritance', () => {
           selector: '[subDir]',
         })
         class SubDirective extends SuperDirective {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -1817,7 +1817,7 @@ describe('inheritance', () => {
           selector: '[sub-dir]',
         })
         class SubDirective extends SuperDirective {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -2118,7 +2118,7 @@ describe('inheritance', () => {
       it('ngOnInit', () => {
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends SuperComponent {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -2159,7 +2159,7 @@ describe('inheritance', () => {
           selector: 'my-comp',
         })
         class MyComponent extends SuperComponent {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -2201,7 +2201,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -2243,7 +2243,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -2285,7 +2285,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -2327,7 +2327,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -2369,7 +2369,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -2422,7 +2422,7 @@ describe('inheritance', () => {
 
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends SuperComponent {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -2675,7 +2675,7 @@ describe('inheritance', () => {
       it('ngOnInit', () => {
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends SuperDirective {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -2717,7 +2717,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -2759,7 +2759,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -2801,7 +2801,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -2843,7 +2843,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -2885,7 +2885,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -2927,7 +2927,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperDirective {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -2983,7 +2983,7 @@ describe('inheritance', () => {
 
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends SuperDirective {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -3296,7 +3296,7 @@ describe('inheritance', () => {
       it('ngOnInit', () => {
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends BareClass {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -3337,7 +3337,7 @@ describe('inheritance', () => {
           selector: 'my-comp',
         })
         class MyComponent extends BareClass {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -3379,7 +3379,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends BareClass {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -3421,7 +3421,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends BareClass {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -3463,7 +3463,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends BareClass {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -3505,7 +3505,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends BareClass {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -3547,7 +3547,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends BareClass {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -3605,7 +3605,7 @@ describe('inheritance', () => {
 
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends BareClass {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -3941,7 +3941,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -3983,7 +3983,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -4025,7 +4025,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -4067,7 +4067,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -4109,7 +4109,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -4151,7 +4151,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -4193,7 +4193,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -4250,7 +4250,7 @@ describe('inheritance', () => {
 
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends SuperComponent {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -4623,7 +4623,7 @@ describe('inheritance', () => {
         focused() {
         }
 
-        clicked() {
+        override clicked() {
           events.push('ChildComponent.clicked');
         }
       }
@@ -4640,7 +4640,7 @@ describe('inheritance', () => {
         blurred() {
         }
 
-        clicked() {
+        override clicked() {
           events.push('GrandChildComponent.clicked');
         }
       }
@@ -4741,7 +4741,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngOnInit() {
+          override ngOnInit() {
             fired.push('sub init');
           }
         }
@@ -4783,7 +4783,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngDoCheck() {
+          override ngDoCheck() {
             fired.push('sub do check');
           }
         }
@@ -4825,7 +4825,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentInit() {
+          override ngAfterContentInit() {
             fired.push('sub after content init');
           }
         }
@@ -4867,7 +4867,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterContentChecked() {
+          override ngAfterContentChecked() {
             fired.push('sub after content checked');
           }
         }
@@ -4909,7 +4909,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewInit() {
+          override ngAfterViewInit() {
             fired.push('sub after view init');
           }
         }
@@ -4951,7 +4951,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngAfterViewChecked() {
+          override ngAfterViewChecked() {
             fired.push('sub after view checked');
           }
         }
@@ -4993,7 +4993,7 @@ describe('inheritance', () => {
           template: `<p>test</p>`,
         })
         class MyComponent extends SuperComponent {
-          ngOnDestroy() {
+          override ngOnDestroy() {
             fired.push('sub destroy');
           }
         }
@@ -5052,7 +5052,7 @@ describe('inheritance', () => {
 
         @Component({selector: 'my-comp', template: `<p>test</p>`})
         class MyComponent extends BareClass {
-          @Input() baz = '';
+          @Input() override baz = '';
 
           @Input() qux = '';
         }
@@ -5182,8 +5182,8 @@ describe('inheritance', () => {
               ],
             })
             class MyComponent extends IntermediateComponent {
-              colorExp = 'color';
-              opacityExp = 'opacity';
+              override colorExp = 'color';
+              override opacityExp = 'opacity';
               bgExp = 'bg';
             }
 
diff --git a/packages/core/test/acceptance/lifecycle_spec.ts b/packages/core/test/acceptance/lifecycle_spec.ts
index e322a78aeb..1bd6ccd4e1 100644
--- a/packages/core/test/acceptance/lifecycle_spec.ts
+++ b/packages/core/test/acceptance/lifecycle_spec.ts
@@ -1253,17 +1253,17 @@ it('should call all hooks in correct order when several directives on same node'
 
   @Directive({selector: 'div'})
   class DirA extends AllHooks {
-    @Input('a') id: number = 0;
+    @Input('a') override id: number = 0;
   }
 
   @Directive({selector: 'div'})
   class DirB extends AllHooks {
-    @Input('b') id: number = 0;
+    @Input('b') override id: number = 0;
   }
 
   @Directive({selector: 'div'})
   class DirC extends AllHooks {
-    @Input('c') id: number = 0;
+    @Input('c') override id: number = 0;
   }
 
   @Component({selector: 'app-comp', template: '<div [a]="1" [b]="2" [c]="3"></div>'})
diff --git a/packages/core/test/acceptance/listener_spec.ts b/packages/core/test/acceptance/listener_spec.ts
index 597d830d03..fe574c23e5 100644
--- a/packages/core/test/acceptance/listener_spec.ts
+++ b/packages/core/test/acceptance/listener_spec.ts
@@ -155,7 +155,7 @@ describe('event listeners', () => {
       let noOfErrors = 0;
 
       class CountingErrorHandler extends ErrorHandler {
-        handleError(error: any): void {
+        override handleError(error: any): void {
           noOfErrors++;
         }
       }
diff --git a/packages/core/test/di/static_injector_spec.ts b/packages/core/test/di/static_injector_spec.ts
index 3106edd9a5..5098e08814 100644
--- a/packages/core/test/di/static_injector_spec.ts
+++ b/packages/core/test/di/static_injector_spec.ts
@@ -33,7 +33,7 @@ class Dashboard {
 }
 
 class TurboEngine extends Engine {
-  static PROVIDER = {provide: Engine, useClass: TurboEngine, deps: []};
+  static override PROVIDER = {provide: Engine, useClass: TurboEngine, deps: []};
 }
 
 class Car {
@@ -65,7 +65,7 @@ class CarWithDashboard {
 }
 
 class SportsCar extends Car {
-  static PROVIDER = {provide: Car, useClass: SportsCar, deps: [Engine]};
+  static override PROVIDER = {provide: Car, useClass: SportsCar, deps: [Engine]};
 }
 
 class CyclicEngine {
diff --git a/packages/core/test/linker/source_map_integration_node_only_spec.ts b/packages/core/test/linker/source_map_integration_node_only_spec.ts
index 256fbf0e41..0b8ac82f4b 100644
--- a/packages/core/test/linker/source_map_integration_node_only_spec.ts
+++ b/packages/core/test/linker/source_map_integration_node_only_spec.ts
@@ -477,7 +477,7 @@ describe('jit source mapping', () => {
   class MockJitEvaluator extends JitEvaluator {
     sources: string[] = [];
 
-    executeFunction(fn: Function, args: any[]) {
+    override executeFunction(fn: Function, args: any[]) {
       // Capture the source that has been generated.
       this.sources.push(fn.toString());
       // Then execute it anyway.
diff --git a/packages/core/test/reflection/reflector_spec.ts b/packages/core/test/reflection/reflector_spec.ts
index 137edb7f88..556182c4cd 100644
--- a/packages/core/test/reflection/reflector_spec.ts
+++ b/packages/core/test/reflection/reflector_spec.ts
@@ -423,7 +423,7 @@ class TestObj {
 
         class Child extends Parent {
           // TODO(issue/24571): remove '!'.
-          @PropDecorator('b2') b!: B;
+          @PropDecorator('b2') override b!: B;
           // TODO(issue/24571): remove '!'.
           @PropDecorator('c') c!: C;
         }
@@ -455,7 +455,7 @@ class TestObj {
         }
 
         class Child extends Parent {
-          hook2() {}
+          override hook2() {}
           hook3() {}
         }
 
@@ -477,7 +477,7 @@ class TestObj {
         }
 
         class Child extends Parent {
-          static decorators = [{type: ClassDecorator, args: [{value: 'child'}]}];
+          static override decorators = [{type: ClassDecorator, args: [{value: 'child'}]}];
         }
 
         class ChildNoDecorators extends Parent {}
@@ -508,7 +508,7 @@ class TestObj {
         class Child extends Parent {}
 
         class ChildWithCtor extends Parent {
-          static ctorParameters = () =>
+          static override ctorParameters = () =>
               [{type: C, decorators: [{type: ParamDecorator, args: ['c']}]},
           ]
           constructor() {
@@ -541,7 +541,7 @@ class TestObj {
         }
 
         class Child extends Parent {
-          static propDecorators: any = {
+          static override propDecorators: any = {
             'b': [{type: PropDecorator, args: ['b2']}],
             'c': [{type: PropDecorator, args: ['c']}],
           };
@@ -568,7 +568,7 @@ class TestObj {
         }
 
         class Child extends Parent {
-          static annotations = [new ClassDecorator({value: 'child'})];
+          static override annotations = [new ClassDecorator({value: 'child'})];
         }
 
         class ChildNoDecorators extends Parent {}
@@ -599,7 +599,7 @@ class TestObj {
         class Child extends Parent {}
 
         class ChildWithCtor extends Parent {
-          static parameters = [
+          static override parameters = [
             [C, new ParamDecorator('c')],
           ];
           constructor() {
@@ -632,7 +632,7 @@ class TestObj {
         }
 
         class Child extends Parent {
-          static propMetadata: any = {
+          static override propMetadata: any = {
             'b': [new PropDecorator('b2')],
             'c': [new PropDecorator('c')],
           };
diff --git a/packages/core/test/render3/jit/declare_factory_spec.ts b/packages/core/test/render3/jit/declare_factory_spec.ts
index 29c4f3a4bd..c3bf765a8d 100644
--- a/packages/core/test/render3/jit/declare_factory_spec.ts
+++ b/packages/core/test/render3/jit/declare_factory_spec.ts
@@ -52,7 +52,7 @@ class DependingClass {
 }
 
 class ChildClass extends DependingClass {
-  static ɵfac =
+  static override ɵfac =
       ɵɵngDeclareFactory({type: ChildClass, deps: null, target: ɵɵFactoryTarget.Injectable});
 }
 
diff --git a/packages/core/test/render3/pipe_spec.ts b/packages/core/test/render3/pipe_spec.ts
index 4cf1f8e841..9e0a2a1312 100644
--- a/packages/core/test/render3/pipe_spec.ts
+++ b/packages/core/test/render3/pipe_spec.ts
@@ -107,7 +107,7 @@ describe('pipe', () => {
       transform() {
         return this.sayHelloService.getHello();
       }
-      static ɵfac = (t?: any) => ɵɵgetInheritedFactory(t || SayHelloPipe)(SayHelloPipe);
+      static override ɵfac = (t?: any) => ɵɵgetInheritedFactory(t || SayHelloPipe)(SayHelloPipe);
       static ɵpipe = ɵɵdefinePipe({name: 'sayHello', type: SayHelloPipe, pure: true});
     }
 
diff --git a/packages/core/test/render3/providers_spec.ts b/packages/core/test/render3/providers_spec.ts
index 82d505b664..921e2c5b82 100644
--- a/packages/core/test/render3/providers_spec.ts
+++ b/packages/core/test/render3/providers_spec.ts
@@ -1293,11 +1293,11 @@ describe('providers', () => {
 
       @addFoo()
       class Parent extends GrandParent {
-        static ɵfac = function Parent_Factory() {};
+        static override ɵfac = function Parent_Factory() {};
       }
 
       class Child extends Parent {
-        static ɵfac = function Child_Factory() {};
+        static override ɵfac = function Child_Factory() {};
       }
 
       expect(ɵɵgetInheritedFactory(Child).name).toBe('Parent_Factory');
@@ -1311,12 +1311,12 @@ describe('providers', () => {
       }
 
       class Parent extends GrandParent {
-        static ɵfac = function Parent_Factory() {};
+        static override ɵfac = function Parent_Factory() {};
       }
 
       @addFoo()
       class Child extends Parent {
-        static ɵfac = function Child_Factory() {};
+        static override ɵfac = function Child_Factory() {};
       }
 
       expect(ɵɵgetInheritedFactory(Child).name).toBe('Parent_Factory');
@@ -1331,11 +1331,11 @@ describe('providers', () => {
       }
 
       class Parent extends GrandParent {
-        static ɵfac = function Parent_Factory() {};
+        static override ɵfac = function Parent_Factory() {};
       }
 
       class Child extends Parent {
-        static ɵfac = function Child_Factory() {};
+        static override ɵfac = function Child_Factory() {};
       }
 
       expect(ɵɵgetInheritedFactory(Child).name).toBe('Parent_Factory');
@@ -1351,12 +1351,12 @@ describe('providers', () => {
 
       @addFoo()
       class Parent extends GrandParent {
-        static ɵfac = function Parent_Factory() {};
+        static override ɵfac = function Parent_Factory() {};
       }
 
       @addFoo()
       class Child extends Parent {
-        static ɵfac = function Child_Factory() {};
+        static override ɵfac = function Child_Factory() {};
       }
 
       expect(ɵɵgetInheritedFactory(Child).name).toBe('Parent_Factory');
@@ -1373,11 +1373,11 @@ describe('providers', () => {
 
          @addFoo()
          class Parent extends GrandParent {
-           static ɵfac = function Parent_Factory() {};
+           static override ɵfac = function Parent_Factory() {};
          }
 
          class Child extends Parent {
-           static ɵfac = function Child_Factory() {};
+           static override ɵfac = function Child_Factory() {};
          }
 
          expect(ɵɵgetInheritedFactory(Child).name).toBe('Parent_Factory');
diff --git a/packages/core/test/testability/testability_spec.ts b/packages/core/test/testability/testability_spec.ts
index 63dd0bffc8..907e64aa2e 100644
--- a/packages/core/test/testability/testability_spec.ts
+++ b/packages/core/test/testability/testability_spec.ts
@@ -26,10 +26,10 @@ function microTask(fn: Function): void {
 @Injectable()
 class MockNgZone extends NgZone {
   /** @internal */
-  onUnstable: EventEmitter<any>;
+  override onUnstable: EventEmitter<any>;
 
   /** @internal */
-  onStable: EventEmitter<any>;
+  override onStable: EventEmitter<any>;
 
   constructor() {
     super({enableLongStackTrace: false});
diff --git a/packages/core/testing/src/ng_zone_mock.ts b/packages/core/testing/src/ng_zone_mock.ts
index e6aae4a7c0..d0f4aa3da0 100644
--- a/packages/core/testing/src/ng_zone_mock.ts
+++ b/packages/core/testing/src/ng_zone_mock.ts
@@ -14,17 +14,17 @@ import {EventEmitter, Injectable, NgZone} from '@angular/core';
  */
 @Injectable()
 export class MockNgZone extends NgZone {
-  onStable: EventEmitter<any> = new EventEmitter(false);
+  override onStable: EventEmitter<any> = new EventEmitter(false);
 
   constructor() {
     super({enableLongStackTrace: false, shouldCoalesceEventChangeDetection: false});
   }
 
-  run(fn: Function): any {
+  override run(fn: Function): any {
     return fn();
   }
 
-  runOutsideAngular(fn: Function): any {
+  override runOutsideAngular(fn: Function): any {
     return fn();
   }