diff --git a/extensions/package.json b/extensions/package.json
index b3469e53913..98261d09a58 100644
--- a/extensions/package.json
+++ b/extensions/package.json
@@ -3,7 +3,7 @@
   "version": "0.0.1",
   "description": "Dependencies shared by all extensions",
   "dependencies": {
-    "typescript": "4.0.3"
+    "typescript": "4.1.1-rc"
   },
   "scripts": {
     "postinstall": "node ./postinstall"
diff --git a/extensions/typescript-language-features/src/languageFeatures/fileConfigurationManager.ts b/extensions/typescript-language-features/src/languageFeatures/fileConfigurationManager.ts
index 03ebff6dd21..eaf2ad0987a 100644
--- a/extensions/typescript-language-features/src/languageFeatures/fileConfigurationManager.ts
+++ b/extensions/typescript-language-features/src/languageFeatures/fileConfigurationManager.ts
@@ -13,18 +13,6 @@ import { isTypeScriptDocument } from '../utils/languageModeIds';
 import { equals } from '../utils/objects';
 import { ResourceMap } from '../utils/resourceMap';
 
-namespace Experimental {
-	// https://github.com/microsoft/TypeScript/pull/37871/
-	export interface UserPreferences extends Proto.UserPreferences {
-		readonly provideRefactorNotApplicableReason?: boolean;
-	}
-
-	// https://github.com/microsoft/TypeScript/issues/41208
-	export interface FormatCodeSettings extends Proto.FormatCodeSettings {
-		readonly insertSpaceAfterOpeningAndBeforeClosingEmptyBraces?: boolean;
-	}
-}
-
 interface FileConfiguration {
 	readonly formatOptions: Proto.FormatCodeSettings;
 	readonly preferences: Proto.UserPreferences;
@@ -141,7 +129,7 @@ export default class FileConfigurationManager extends Disposable {
 	private getFormatOptions(
 		document: vscode.TextDocument,
 		options: vscode.FormattingOptions
-	): Experimental.FormatCodeSettings {
+	): Proto.FormatCodeSettings {
 		const config = vscode.workspace.getConfiguration(
 			isTypeScriptDocument(document) ? 'typescript.format' : 'javascript.format',
 			document.uri);
@@ -185,7 +173,7 @@ export default class FileConfigurationManager extends Disposable {
 			isTypeScriptDocument(document) ? 'typescript.preferences' : 'javascript.preferences',
 			document.uri);
 
-		const preferences: Experimental.UserPreferences = {
+		const preferences: Proto.UserPreferences = {
 			quotePreference: this.getQuoteStylePreference(preferencesConfig),
 			importModuleSpecifierPreference: getImportModuleSpecifierPreference(preferencesConfig),
 			importModuleSpecifierEnding: getImportModuleSpecifierEndingPreference(preferencesConfig),
diff --git a/extensions/typescript-language-features/src/languageFeatures/refactor.ts b/extensions/typescript-language-features/src/languageFeatures/refactor.ts
index ab0186c8f01..b74e90c18de 100644
--- a/extensions/typescript-language-features/src/languageFeatures/refactor.ts
+++ b/extensions/typescript-language-features/src/languageFeatures/refactor.ts
@@ -20,11 +20,6 @@ import FormattingOptionsManager from './fileConfigurationManager';
 
 const localize = nls.loadMessageBundle();
 
-namespace Experimental {
-	export interface RefactorActionInfo extends Proto.RefactorActionInfo {
-		readonly notApplicableReason?: string;
-	}
-}
 
 interface DidApplyRefactoringCommand_Args {
 	readonly codeAction: InlinedCodeAction
@@ -354,7 +349,7 @@ class TypeScriptRefactorProvider implements vscode.CodeActionProvider<TsCodeActi
 	}
 
 	private refactorActionToCodeAction(
-		action: Experimental.RefactorActionInfo,
+		action: Proto.RefactorActionInfo,
 		document: vscode.TextDocument,
 		info: Proto.ApplicableRefactorInfo,
 		rangeOrSelection: vscode.Range | vscode.Selection,
diff --git a/extensions/typescript-language-features/src/typeScriptServiceClientHost.ts b/extensions/typescript-language-features/src/typeScriptServiceClientHost.ts
index d225ef60224..76471a20432 100644
--- a/extensions/typescript-language-features/src/typeScriptServiceClientHost.ts
+++ b/extensions/typescript-language-features/src/typeScriptServiceClientHost.ts
@@ -30,12 +30,6 @@ import * as typeConverters from './utils/typeConverters';
 import TypingsStatus, { AtaProgressReporter } from './utils/typingsStatus';
 import * as ProjectStatus from './utils/largeProjectStatus';
 
-namespace Experimental {
-	export interface Diagnostic extends Proto.Diagnostic {
-		readonly reportsDeprecated?: {}
-	}
-}
-
 // Style check diagnostics that can be reported as warnings
 const styleCheckDiagnostics = new Set([
 	...errorCodes.variableDeclaredButNeverUsed,
@@ -256,7 +250,7 @@ export default class TypeScriptServiceClientHost extends Disposable {
 		return diagnostics.map(tsDiag => this.tsDiagnosticToVsDiagnostic(tsDiag, source));
 	}
 
-	private tsDiagnosticToVsDiagnostic(diagnostic: Experimental.Diagnostic, source: string): vscode.Diagnostic & { reportUnnecessary: any, reportDeprecated: any } {
+	private tsDiagnosticToVsDiagnostic(diagnostic: Proto.Diagnostic, source: string): vscode.Diagnostic & { reportUnnecessary: any, reportDeprecated: any } {
 		const { start, end, text } = diagnostic;
 		const range = new vscode.Range(typeConverters.Position.fromLocation(start), typeConverters.Position.fromLocation(end));
 		const converted = new vscode.Diagnostic(range, text, this.getDiagnosticSeverity(diagnostic));
diff --git a/extensions/yarn.lock b/extensions/yarn.lock
index 20586e5c587..059ea7481b6 100644
--- a/extensions/yarn.lock
+++ b/extensions/yarn.lock
@@ -2,7 +2,7 @@
 # yarn lockfile v1
 
 
-typescript@4.0.3:
-  version "4.0.3"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.0.3.tgz#153bbd468ef07725c1df9c77e8b453f8d36abba5"
-  integrity sha512-tEu6DGxGgRJPb/mVPIZ48e69xCn2yRmCgYmDugAVwmJ6o+0u1RI18eO7E7WBTLYLaEVVOhwQmcdhQHweux/WPg==
+typescript@4.1.1-rc:
+  version "4.1.1-rc"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.1.1-rc.tgz#4a335244b9b2754995849ca4b607c74d6ee73719"
+  integrity sha512-tgNcFrLIjlaMWEc7bKC0bxLNIt8BIAauY/HLUOQDyTP75HGskETtXOt46x4EKAHRKhWVLMc7yM02puTHa/yhCA==