diff --git a/src/vs/platform/environment/common/environment.ts b/src/vs/platform/environment/common/environment.ts
index aa4e77e37d76ff53aa7fd7c833fc86a4ed0208cf..9a0cc09ce5d8670bcbaf4d830e0d88f1e36e1661 100644
--- a/src/vs/platform/environment/common/environment.ts
+++ b/src/vs/platform/environment/common/environment.ts
@@ -73,6 +73,7 @@ export interface ParsedArgs {
 	'disable-user-env-probe'?: boolean;
 	'force'?: boolean;
 	'force-user-env'?: boolean;
+	'sync'?: 'on' | 'off';
 
 	// chromium command line args: https://electronjs.org/docs/all#supported-chrome-command-line-switches
 	'no-proxy-server'?: boolean;
diff --git a/src/vs/platform/environment/node/argv.ts b/src/vs/platform/environment/node/argv.ts
index 5f2498445f74f5a4b830a49f9b11bfbce4ac37e2..f6f818485d92bf1a3bc950645abd5037dbf6a280 100644
--- a/src/vs/platform/environment/node/argv.ts
+++ b/src/vs/platform/environment/node/argv.ts
@@ -52,6 +52,7 @@ export const OPTIONS: OptionDescriptions<Required<ParsedArgs>> = {
 	'telemetry': { type: 'boolean', cat: 'o', description: localize('telemetry', "Shows all telemetry events which VS code collects.") },
 	'folder-uri': { type: 'string[]', cat: 'o', args: 'uri', description: localize('folderUri', "Opens a window with given folder uri(s)") },
 	'file-uri': { type: 'string[]', cat: 'o', args: 'uri', description: localize('fileUri', "Opens a window with given file uri(s)") },
+	'sync': { type: 'string', cat: 'o', description: localize('turn sync', "Turn sync on or off"), args: ['on', 'off'] },
 
 	'extensions-dir': { type: 'string', deprecates: 'extensionHomePath', cat: 'e', args: 'dir', description: localize('extensionHomePath', "Set the root path for extensions.") },
 	'builtin-extensions-dir': { type: 'string' },
diff --git a/src/vs/platform/userDataSync/common/userDataSyncEnablementService.ts b/src/vs/platform/userDataSync/common/userDataSyncEnablementService.ts
index 7f9e8a23b873b28d98bafe7c1969f7512d71161d..250dcbe66ebc7784a2035cd52093ca3b9022647a 100644
--- a/src/vs/platform/userDataSync/common/userDataSyncEnablementService.ts
+++ b/src/vs/platform/userDataSync/common/userDataSyncEnablementService.ts
@@ -8,6 +8,7 @@ import { Disposable } from 'vs/base/common/lifecycle';
 import { Emitter, Event } from 'vs/base/common/event';
 import { IStorageService, IWorkspaceStorageChangeEvent, StorageScope } from 'vs/platform/storage/common/storage';
 import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
+import { IEnvironmentService } from 'vs/platform/environment/common/environment';
 
 type SyncEnablementClassification = {
 	enabled?: { classification: 'SystemMetaData', purpose: 'FeatureInsight', isMeasurement: true };
@@ -29,8 +30,17 @@ export class UserDataSyncEnablementService extends Disposable implements IUserDa
 	constructor(
 		@IStorageService private readonly storageService: IStorageService,
 		@ITelemetryService private readonly telemetryService: ITelemetryService,
+		@IEnvironmentService environmentService: IEnvironmentService,
 	) {
 		super();
+		switch (environmentService.args['sync']) {
+			case 'on':
+				this.setEnablement(true);
+				break;
+			case 'off':
+				this.setEnablement(false);
+				break;
+		}
 		this._register(storageService.onDidChangeStorage(e => this.onDidStorageChange(e)));
 	}