diff --git a/Jakefile.js b/Jakefile.js
index ed4751c47f4..0c764758240 100644
--- a/Jakefile.js
+++ b/Jakefile.js
@@ -695,6 +695,7 @@ function runTestsAndWriteOutput(file) {
     cleanTestDirs();
     var tests = process.env.test || process.env.tests || process.env.t;
     var light = process.env.light || false;
+    var beep = process.env.beep;
     var testConfigFile = 'test.config';
     if (fs.existsSync(testConfigFile)) {
         fs.unlinkSync(testConfigFile);
@@ -726,6 +727,7 @@ function runTestsAndWriteOutput(file) {
     var tapNotOk = /^not\sok/;
     var tapComment = /^#/;
     var typeError = /^\s+TypeError:/;
+    var debugError = /^\s+Error:\sDebug\sFailure\./;
     var progress = new ProgressBar("Running tests...");
     var expectedTestCount = 0;
     var testCount = 0;
@@ -733,6 +735,7 @@ function runTestsAndWriteOutput(file) {
     var successCount = 0;
     var comments = [];
     var typeErrorCount = 0;
+    var debugErrorCount = 0;
 
     ex.addListener("stdout", function (output) {
         var m = tapRange.exec(output);
@@ -756,6 +759,9 @@ function runTestsAndWriteOutput(file) {
             else if (typeError.test(output)) {
                 typeErrorCount++;
             }
+            else if (debugError.test(output)) {
+                debugErrorCount++;
+            }
             return;
         }
 
@@ -790,6 +796,8 @@ function runTestsAndWriteOutput(file) {
         console.log(comments.join(os.EOL));
         deleteTemporaryProjectOutput();
         complete();
+
+        if (beep) process.stdout.write("\u0007");
     });
     ex.addListener("error", function (e, status) {
         if (progress.visible) {
@@ -803,7 +811,12 @@ function runTestsAndWriteOutput(file) {
             console.log("# type errors: %s", typeErrorCount);
         }
 
+        if (debugErrorCount) {
+            console.log("# debug errors: %s", debugErrorCount);
+        }
+
         deleteTemporaryProjectOutput();
+        if (beep) process.stdout.write("\u0007");
         fail("Process exited with code " + status);
     });
     ex.run();
diff --git a/src/compiler/transformers/module/es6.ts b/src/compiler/transformers/module/es6.ts
index 63b147b6e60..f513ac36dbb 100644
--- a/src/compiler/transformers/module/es6.ts
+++ b/src/compiler/transformers/module/es6.ts
@@ -4,9 +4,35 @@
 /*@internal*/
 namespace ts {
     export function transformES6Module(context: TransformationContext) {
+        const compilerOptions = context.getCompilerOptions();
+        const resolver = context.getEmitResolver();
+
+        let currentSourceFile: SourceFile;
+
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isExternalModule(node) || compilerOptions.isolatedModules) {
+                currentSourceFile = node;
+                return visitEachChild(node, visitor, context);
+            }
+            return node;
+        }
+
+        function visitor(node: Node) {
+            switch (node.kind) {
+                case SyntaxKind.ImportDeclaration:
+                    return visitImportDeclaration(<ImportDeclaration>node);
+            }
+
+            return node;
+        }
+
+        function visitImportDeclaration(node: ImportDeclaration) {
+            if (node.importClause && !resolver.isReferencedAliasDeclaration(node.importClause, /*checkChildren*/ true)) {
+                return undefined;
+            }
+
             return node;
         }
     }
diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index c49cdc49821..19e317b6cba 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -1793,11 +1793,14 @@ namespace ts {
                 return undefined;
             }
 
-            return createMethod(
-                visitNodes(node.modifiers, visitor, isModifier),
-                visitPropertyNameOfClassElement(node),
-                visitNodes(node.parameters, visitor, isParameter),
-                transformFunctionBody(node),
+            return setOriginalNode(
+                createMethod(
+                    visitNodes(node.modifiers, visitor, isModifier),
+                    visitPropertyNameOfClassElement(node),
+                    visitNodes(node.parameters, visitor, isParameter),
+                    transformFunctionBody(node),
+                    node
+                ),
                 node
             );
         }
@@ -1900,6 +1903,10 @@ namespace ts {
          * @param node The function expression node.
          */
         function visitFunctionExpression(node: FunctionExpression) {
+            if (nodeIsMissing(node.body)) {
+                return createNode(SyntaxKind.OmittedExpression);
+            }
+
             return createFunctionExpression(
                 node.asteriskToken,
                 node.name,
@@ -1916,7 +1923,7 @@ namespace ts {
          * @param node The declaration node.
          */
         function shouldElideFunctionLikeDeclaration(node: FunctionLikeDeclaration) {
-            return node.body === undefined
+            return nodeIsMissing(node.body)
                 || hasModifier(node, ModifierFlags.Abstract | ModifierFlags.Ambient);
         }
 
@@ -2004,7 +2011,7 @@ namespace ts {
                     )
                 );
 
-                const block = createBlock(statements, /*location*/ node.body);
+                const block = createBlock(statements, /*location*/ node.body, /*multiLine*/ true);
 
                 // Minor optimization, emit `_super` helper to capture `super` access in an arrow.
                 // This step isn't needed if we eventually transform this to ES5.
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 18a95bc5ff0..aedd44fcb6a 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -3405,6 +3405,7 @@ namespace ts {
             || kind === SyntaxKind.TypeAliasDeclaration
             || kind === SyntaxKind.EnumDeclaration
             || kind === SyntaxKind.ModuleDeclaration
+            || kind === SyntaxKind.ImportDeclaration
             || kind === SyntaxKind.ImportEqualsDeclaration
             || kind === SyntaxKind.ExportDeclaration
             || kind === SyntaxKind.ExportAssignment;