diff --git a/src/vs/platform/product/common/product.ts b/src/vs/platform/product/common/product.ts
index 2730ee7..4d46c23 100644
--- a/src/vs/platform/product/common/product.ts
+++ b/src/vs/platform/product/common/product.ts
@@ -8,6 +8,7 @@ import { isWeb } from 'vs/base/common/platform';
 import { env } from 'vs/base/common/process';
 import { FileAccess } from 'vs/base/common/network';
 import { dirname, joinPath } from 'vs/base/common/resources';
+import { getDefaultUserDataPath } from 'vs/base/node/userDataPath';
 
 let product: IProductConfiguration;
 
@@ -47,6 +48,29 @@ else {
 	product = require.__$__nodeRequire(joinPath(rootPath, 'product.json').fsPath);
 	const pkg = require.__$__nodeRequire(joinPath(rootPath, 'package.json').fsPath) as { version: string; };
 
+	// Merge user-customized product.json
+	try {
+		const merge = (...objects: any[]) =>
+			objects.reduce((result, current) => {
+				Object.keys(current).forEach((key) => {
+					if (Array.isArray(result[key]) && Array.isArray(current[key])) {
+						result[key] = current[key];
+					} else if (typeof result[key] === 'object' && typeof current[key] === 'object') {
+						result[key] = merge(result[key], current[key]);
+					} else {
+						result[key] = current[key];
+					}
+				});
+
+				return result;
+			}, {}) as any;
+
+		const userProduct = require.__$__nodeRequire(joinPath(FileAccess.asFileUri(getDefaultUserDataPath(), require), 'product.json').fsPath);
+
+		product = merge(product, userProduct)
+	} catch (ex) {
+	}
+
 	// Running out of sources
 	if (env['VSCODE_DEV']) {
 		Object.assign(product, {
@@ -56,6 +80,19 @@ else {
 		});
 	}
 
+	// Set user-defined extension gallery
+	const { serviceUrl, cacheUrl, itemUrl, controlUrl, recommendationsUrl } = product.extensionsGallery || {}
+
+	Object.assign(product, {
+		extensionsGallery: {
+			serviceUrl: env['VSCODE_GALLERY_SERVICE_URL'] || serviceUrl,
+			cacheUrl: env['VSCODE_GALLERY_CACHE_URL'] || cacheUrl,
+			itemUrl: env['VSCODE_GALLERY_ITEM_URL'] || itemUrl,
+			controlUrl: env['VSCODE_GALLERY_CONTROL_URL'] || controlUrl,
+			recommendationsUrl: env['VSCODE_GALLERY_RECOMMENDATIONS_URL'] || recommendationsUrl
+		}
+	})
+
 	Object.assign(product, {
 		version: pkg.version
 	});
diff --git a/src/vs/platform/product/common/productService.ts b/src/vs/platform/product/common/productService.ts
index 07263ca..0328f58 100644
--- a/src/vs/platform/product/common/productService.ts
+++ b/src/vs/platform/product/common/productService.ts
@@ -67,6 +67,7 @@ export interface IProductConfiguration {
 
 	readonly extensionsGallery?: {
 		readonly serviceUrl: string;
+		readonly cacheUrl?: string;
 		readonly itemUrl: string;
 		readonly controlUrl: string;
 		readonly recommendationsUrl: string;