diff --git a/scripts/importTypescript.js b/scripts/importTypescript.js
index cade4cb2..d1e42d22 100644
--- a/scripts/importTypescript.js
+++ b/scripts/importTypescript.js
@@ -19,7 +19,7 @@ const TYPESCRIPT_LIB_DESTINATION = path.join(__dirname, '../src/lib');
 	importLibs();
 
 	const npmLsOutput = JSON.parse(child_process.execSync("npm ls typescript --depth=0 --json=true").toString());
-	const typeScriptDependencyVersion = npmLsOutput.dependencies.typescript.version;
+	const typeScriptDependencyVersion = '3.5.1';//npmLsOutput.dependencies.typescript.version;
 
 	fs.writeFileSync(
 		path.join(TYPESCRIPT_LIB_DESTINATION, 'typescriptServicesMetadata.ts'),
@@ -34,10 +34,22 @@ const TYPESCRIPT_LIB_DESTINATION = path.join(__dirname, '../src/lib');
 		tsServices.replace(/\n    ts\.sys =([^]*)\n    \}\)\(\);/m, `\n    // MONACOCHANGE\n    ts.sys = undefined;\n    // END MONACOCHANGE`)
 	);
 
-	// Eliminate another require() call...
-	tsServices = (
-		tsServices.replace(/return require\(fileNameToRequire\);/, `// MONACOCHANGE\n            return undefined;\n            // END MONACOCHANGE`)
-	);
+	// Eliminate more require() calls...
+	tsServices = tsServices.replace(/^( +)etwModule = require\(.*$/m, '$1// MONACOCHANGE\n$1etwModule = undefined;\n$1// END MONACOCHANGE');
+	tsServices = tsServices.replace(/^( +)var result = ts\.sys\.require\(.*$/m, '$1// MONACOCHANGE\n$1var result = undefined;\n$1// END MONACOCHANGE');
+
+	// Flag any new require calls (outside comments) so they can be corrected preemptively.
+	// To avoid missing cases (or using an even more complex regex), temporarily remove comments
+	// about require() and then check for lines actually calling require().
+	// \/[*/] matches the start of a comment (single or multi-line).
+	// ^\s+\*[^/] matches (presumably) a later line of a multi-line comment.
+	const tsServicesNoCommentedRequire = tsServices.replace(/(\/[*/]|^\s+\*[^/]).*\brequire\(.*/gm, '');
+	const linesWithRequire = tsServicesNoCommentedRequire.match(/^.*?\brequire\(.*$/gm);
+	if (linesWithRequire && linesWithRequire.length) {
+		console.error('Found new require() calls on the following lines. These should be removed to avoid breaking webpack builds.\n');
+		console.error(linesWithRequire.join('\n'));
+		process.exit(1);
+	}
 
 	// Make sure process.args don't get called in the browser, this
 	// should only happen in TS 2.6.2
diff --git a/src/languageFeatures.ts b/src/languageFeatures.ts
index 7dc0d1de..da5e4207 100644
--- a/src/languageFeatures.ts
+++ b/src/languageFeatures.ts
@@ -181,6 +181,7 @@ export class DiagnosticsAdapter extends Adapter {
 			}
 			const markers = diagnostics
 				.reduce((p, c) => c.concat(p), [])
+				.filter(d => (this._defaults.getDiagnosticsOptions().diagnosticCodesToIgnore || []).indexOf(d.code) === -1)
 				.map(d => this._convertDiagnostics(resource, d));
 
 			monaco.editor.setModelMarkers(monaco.editor.getModel(resource), this._selector, markers);
@@ -200,10 +201,32 @@ export class DiagnosticsAdapter extends Adapter {
 			endLineNumber,
 			endColumn,
 			message: flattenDiagnosticMessageText(diag.messageText, '\n'),
-			code: diag.code.toString()
+			code: diag.code.toString(),
+			tags: diag.reportsUnnecessary ? [monaco.MarkerTag.Unnecessary] : [],
+			relatedInformation: this._convertRelatedInformation(resource, diag.relatedInformation),
 		};
 	}
 
+	private _convertRelatedInformation(resource: Uri, relatedInformation?: ts.DiagnosticRelatedInformation[]): monaco.editor.IRelatedInformation[] {
+		if (relatedInformation === undefined)
+			return undefined;
+
+		return relatedInformation.map(info => {
+			const relatedResource = info.file === undefined ? resource : monaco.Uri.parse(info.file.fileName);
+			const { lineNumber: startLineNumber, column: startColumn } = this._offsetToPosition(relatedResource, info.start);
+			const { lineNumber: endLineNumber, column: endColumn } = this._offsetToPosition(relatedResource, info.start + info.length);
+
+			return {
+				resource: relatedResource,
+				startLineNumber,
+				startColumn,
+				endLineNumber,
+				endColumn,
+				message: flattenDiagnosticMessageText(info.messageText, '\n')
+			};
+		});
+	}
+
 	private _tsDiagnosticCategoryToMarkerSeverity(category: ts.DiagnosticCategory): monaco.MarkerSeverity {
 		switch (category) {
 			case ts.DiagnosticCategory.Error: return monaco.MarkerSeverity.Error
diff --git a/src/lib/typescriptServices-amd.js b/src/lib/typescriptServices-amd.js
index f9b12bf1..8cbc099e 100644
--- a/src/lib/typescriptServices-amd.js
+++ b/src/lib/typescriptServices-amd.js
@@ -2349,7 +2349,9 @@ var ts;
             try {
                 if (ts.sys && ts.sys.require) {
                     var basePath = ts.getDirectoryPath(ts.resolvePath(ts.sys.getExecutingFilePath()));
-                    var result = ts.sys.require(basePath, "./compiler-debug");
+                    // MONACOCHANGE
+                    var result = undefined;
+                    // END MONACOCHANGE
                     if (!result.error) {
                         result.module.init(ts);
                         extendedDebugModule = result.module;
@@ -2515,7 +2517,9 @@ var ts;
     try {
         // require() will throw an exception if the module is not installed
         // It may also return undefined if not installed properly
-        etwModule = require("@microsoft/typescript-etw");
+        // MONACOCHANGE
+        etwModule = undefined;
+        // END MONACOCHANGE
     }
     catch (e) {
         etwModule = undefined;
diff --git a/src/lib/typescriptServices.js b/src/lib/typescriptServices.js
index ce4e12a9..47543b59 100644
--- a/src/lib/typescriptServices.js
+++ b/src/lib/typescriptServices.js
@@ -2349,7 +2349,9 @@ var ts;
             try {
                 if (ts.sys && ts.sys.require) {
                     var basePath = ts.getDirectoryPath(ts.resolvePath(ts.sys.getExecutingFilePath()));
-                    var result = ts.sys.require(basePath, "./compiler-debug");
+                    // MONACOCHANGE
+                    var result = undefined;
+                    // END MONACOCHANGE
                     if (!result.error) {
                         result.module.init(ts);
                         extendedDebugModule = result.module;
@@ -2515,7 +2517,9 @@ var ts;
     try {
         // require() will throw an exception if the module is not installed
         // It may also return undefined if not installed properly
-        etwModule = require("@microsoft/typescript-etw");
+        // MONACOCHANGE
+        etwModule = undefined;
+        // END MONACOCHANGE
     }
     catch (e) {
         etwModule = undefined;
diff --git a/src/lib/typescriptServicesMetadata.ts b/src/lib/typescriptServicesMetadata.ts
index c2d37d7c..433e642e 100644
--- a/src/lib/typescriptServicesMetadata.ts
+++ b/src/lib/typescriptServicesMetadata.ts
@@ -1 +1 @@
-export const typescriptVersion = "3.7.2";
+export const typescriptVersion = "3.5.1";
diff --git a/src/monaco.d.ts b/src/monaco.d.ts
index 8aa58804..7d50e7ab 100644
--- a/src/monaco.d.ts
+++ b/src/monaco.d.ts
@@ -129,6 +129,7 @@ declare module monaco.languages.typescript {
         noSemanticValidation?: boolean;
         noSyntaxValidation?: boolean;
         noSuggestionDiagnostics?: boolean;
+        diagnosticCodesToIgnore?: number[];
     }
 
     export interface LanguageServiceDefaults {
diff --git a/src/tsconfig.esm.json b/src/tsconfig.esm.json
index 6efc6a00..d6085367 100644
--- a/src/tsconfig.esm.json
+++ b/src/tsconfig.esm.json
@@ -2,6 +2,7 @@
   "compilerOptions": {
     "module": "esnext",
     "moduleResolution": "node",
+    "declaration": true,
     "outDir": "../release/esm",
     "target": "es5",
     "lib": [
diff --git a/src/tsconfig.json b/src/tsconfig.json
index 778087ca..2dbccb11 100644
--- a/src/tsconfig.json
+++ b/src/tsconfig.json
@@ -3,6 +3,7 @@
     "module": "amd",
     "moduleResolution": "node",
     "outDir": "../release/dev",
+    "declaration": true,
     "target": "es5",
     "lib": [
       "dom",