diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 2bedb42dca6..8405985b272 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16388,14 +16388,11 @@ namespace ts {
         function checkSourceFileWorker(node: SourceFile) {
             const links = getNodeLinks(node);
             if (!(links.flags & NodeCheckFlags.TypeChecked)) {
-                // Check whether the file has declared it is the default lib,
-                // and whether the user has specifically chosen to avoid checking it.
-                if (compilerOptions.skipDefaultLibCheck) {
-                    // If the user specified '--noLib' and a file has a '/// <reference no-default-lib="true"/>',
-                    // then we should treat that file as a default lib.
-                    if (node.hasNoDefaultLib) {
-                        return;
-                    }
+                // If skipLibCheck is enabled, skip type checking if file is a declaration file.
+                // If skipDefaultLibCheck is enabled, skip type checking if file contains a
+                // '/// <reference no-default-lib="true"/>' directive.
+                if (compilerOptions.skipLibCheck && node.isDeclarationFile || compilerOptions.skipDefaultLibCheck && node.hasNoDefaultLib) {
+                    return;
                 }
 
                 // Grammar checking
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index a8d955d3b16..80d7f0b1f16 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -139,6 +139,11 @@ namespace ts {
             name: "skipDefaultLibCheck",
             type: "boolean",
         },
+        {
+            name: "skipLibCheck",
+            type: "boolean",
+            description: Diagnostics.Skip_type_checking_of_declaration_files,
+        },
         {
             name: "out",
             type: "string",
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 4eb16c5bcb0..9942a71df3b 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -443,7 +443,7 @@
         "category": "Error",
         "code": 1147
     },
-    "Cannot compile modules unless the '--module' flag is provided with a valid module type. Consider setting the 'module' compiler option in a 'tsconfig.json' file.": {
+    "Cannot use imports, exports, or module augmentations when '--module' is 'none'.": {
         "category": "Error",
         "code": 1148
     },
@@ -2296,7 +2296,7 @@
         "category": "Error",
         "code": 5062
     },
-    "Substututions for pattern '{0}' should be an array.": {
+    "Substitutions for pattern '{0}' should be an array.": {
         "category": "Error",
         "code": 5063
     },
@@ -2348,6 +2348,10 @@
         "category": "Message",
         "code": 6011
     },
+    "Skip type checking of declaration files.": {
+        "category": "Message",
+        "code": 6012
+    },
     "Specify ECMAScript target version: 'ES3' (default), 'ES5', or 'ES2015'": {
         "category": "Message",
         "code": 6015
@@ -2751,7 +2755,12 @@
     "Resolving real path for '{0}', result '{1}'": {
         "category": "Message",
         "code": 6130
-    },    
+    },
+    "Cannot compile modules using option '{0}' unless the '--module' flag is 'amd' or 'system'.": {
+        "category": "Error",
+        "code": 6131
+    },
+
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 52547cb165d..6b2a5c0def4 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -2021,7 +2021,7 @@ namespace ts {
                         }
                     }
                     else {
-                        programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Substututions_for_pattern_0_should_be_an_array, key));
+                        programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Substitutions_for_pattern_0_should_be_an_array, key));
                     }
                 }
             }
@@ -2080,7 +2080,7 @@ namespace ts {
             else if (firstExternalModuleSourceFile && languageVersion < ScriptTarget.ES6 && options.module === ModuleKind.None) {
                 // We cannot use createDiagnosticFromNode because nodes do not have parents yet
                 const span = getErrorSpanForNode(firstExternalModuleSourceFile, firstExternalModuleSourceFile.externalModuleIndicator);
-                programDiagnostics.add(createFileDiagnostic(firstExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_compile_modules_unless_the_module_flag_is_provided_with_a_valid_module_type_Consider_setting_the_module_compiler_option_in_a_tsconfig_json_file));
+                programDiagnostics.add(createFileDiagnostic(firstExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_use_imports_exports_or_module_augmentations_when_module_is_none));
             }
 
             // Cannot specify module gen target of es6 when below es6
@@ -2089,8 +2089,14 @@ namespace ts {
             }
 
             // Cannot specify module gen that isn't amd or system with --out
-            if (outFile && options.module && !(options.module === ModuleKind.AMD || options.module === ModuleKind.System)) {
-                programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Only_amd_and_system_modules_are_supported_alongside_0, options.out ? "out" : "outFile"));
+            if (outFile) {
+                if (options.module && !(options.module === ModuleKind.AMD || options.module === ModuleKind.System)) {
+                    programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Only_amd_and_system_modules_are_supported_alongside_0, options.out ? "out" : "outFile"));
+                }
+                else if (options.module === undefined && firstExternalModuleSourceFile) {
+                    const span = getErrorSpanForNode(firstExternalModuleSourceFile, firstExternalModuleSourceFile.externalModuleIndicator);
+                    programDiagnostics.add(createFileDiagnostic(firstExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_compile_modules_using_option_0_unless_the_module_flag_is_amd_or_system, options.out ? "out" : "outFile"));
+                }
             }
 
             // there has to be common source directory if user specified --outdir || --sourceRoot
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 15fd2bd4fcf..689812ed419 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2505,6 +2505,7 @@ namespace ts {
         allowJs?: boolean;
         noImplicitUseStrict?: boolean;
         strictNullChecks?: boolean;
+        skipLibCheck?: boolean;
         listEmittedFiles?: boolean;
         lib?: string[];
         /* @internal */ stripInternal?: boolean;
diff --git a/src/services/services.ts b/src/services/services.ts
index ef25fae7bba..ab289c10cf0 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1542,68 +1542,74 @@ namespace ts {
         export const unknown = "";
         export const warning = "warning";
 
-        // predefined type (void) or keyword (class)
+        /** predefined type (void) or keyword (class) */
         export const keyword = "keyword";
 
-        // top level script node
+        /** top level script node */
         export const scriptElement = "script";
 
-        // module foo {}
+        /** module foo {} */
         export const moduleElement = "module";
 
-        // class X {}
+        /** class X {} */
         export const classElement = "class";
 
-        // var x = class X {}
+        /** var x = class X {} */
         export const localClassElement = "local class";
 
-        // interface Y {}
+        /** interface Y {} */
         export const interfaceElement = "interface";
 
-        // type T = ...
+        /** type T = ... */
         export const typeElement = "type";
 
-        // enum E
+        /** enum E */
         export const enumElement = "enum";
 
-        // Inside module and script only
-        // const v = ..
+        /**
+         * Inside module and script only
+         * const v = ..
+         */
         export const variableElement = "var";
 
-        // Inside function
+        /** Inside function */
         export const localVariableElement = "local var";
 
-        // Inside module and script only
-        // function f() { }
+        /**
+         * Inside module and script only
+         * function f() { }
+         */
         export const functionElement = "function";
 
-        // Inside function
+        /** Inside function */
         export const localFunctionElement = "local function";
 
-        // class X { [public|private]* foo() {} }
+        /** class X { [public|private]* foo() {} } */
         export const memberFunctionElement = "method";
 
-        // class X { [public|private]* [get|set] foo:number; }
+        /** class X { [public|private]* [get|set] foo:number; } */
         export const memberGetAccessorElement = "getter";
         export const memberSetAccessorElement = "setter";
 
-        // class X { [public|private]* foo:number; }
-        // interface Y { foo:number; }
+        /**
+         * class X { [public|private]* foo:number; }
+         * interface Y { foo:number; }
+         */
         export const memberVariableElement = "property";
 
-        // class X { constructor() { } }
+        /** class X { constructor() { } } */
         export const constructorImplementationElement = "constructor";
 
-        // interface Y { ():number; }
+        /** interface Y { ():number; } */
         export const callSignatureElement = "call";
 
-        // interface Y { []:number; }
+        /** interface Y { []:number; } */
         export const indexSignatureElement = "index";
 
-        // interface Y { new():Y; }
+        /** interface Y { new():Y; } */
         export const constructSignatureElement = "construct";
 
-        // function foo(*Y*: string)
+        /** function foo(*Y*: string) */
         export const parameterElement = "parameter";
 
         export const typeParameterElement = "type parameter";
@@ -4946,8 +4952,7 @@ namespace ts {
         function getDocumentHighlights(fileName: string, position: number, filesToSearch: string[]): DocumentHighlights[] {
             synchronizeHostData();
 
-            filesToSearch = map(filesToSearch, normalizeSlashes);
-            const sourceFilesToSearch = filter(program.getSourceFiles(), f => contains(filesToSearch, f.fileName));
+            const sourceFilesToSearch = map(filesToSearch, f => program.getSourceFile(f));
             const sourceFile = getValidSourceFile(fileName);
 
             const node = getTouchingWord(sourceFile, position);
diff --git a/tests/baselines/reference/isolatedModulesOut.errors.txt b/tests/baselines/reference/isolatedModulesOut.errors.txt
index 7d16ac94666..157ae98fcb3 100644
--- a/tests/baselines/reference/isolatedModulesOut.errors.txt
+++ b/tests/baselines/reference/isolatedModulesOut.errors.txt
@@ -1,11 +1,14 @@
 error TS5053: Option 'out' cannot be specified with option 'isolatedModules'.
+tests/cases/compiler/file1.ts(2,1): error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
 tests/cases/compiler/file2.ts(1,1): error TS1208: Cannot compile namespaces when the '--isolatedModules' flag is provided.
 
 
 !!! error TS5053: Option 'out' cannot be specified with option 'isolatedModules'.
-==== tests/cases/compiler/file1.ts (0 errors) ====
+==== tests/cases/compiler/file1.ts (1 errors) ====
     
     export var x;
+    ~~~~~~~~~~~~~
+!!! error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
 ==== tests/cases/compiler/file2.ts (1 errors) ====
     var y;
     ~~~
diff --git a/tests/baselines/reference/moduleNoneErrors.errors.txt b/tests/baselines/reference/moduleNoneErrors.errors.txt
index cb943050fa8..4838b99f85b 100644
--- a/tests/baselines/reference/moduleNoneErrors.errors.txt
+++ b/tests/baselines/reference/moduleNoneErrors.errors.txt
@@ -1,10 +1,10 @@
-tests/cases/compiler/a.ts(1,14): error TS1148: Cannot compile modules unless the '--module' flag is provided with a valid module type. Consider setting the 'module' compiler option in a 'tsconfig.json' file.
+tests/cases/compiler/a.ts(1,14): error TS1148: Cannot use imports, exports, or module augmentations when '--module' is 'none'.
 
 
 ==== tests/cases/compiler/a.ts (1 errors) ====
     export class Foo {
                  ~~~
-!!! error TS1148: Cannot compile modules unless the '--module' flag is provided with a valid module type. Consider setting the 'module' compiler option in a 'tsconfig.json' file.
+!!! error TS1148: Cannot use imports, exports, or module augmentations when '--module' is 'none'.
         foo: string;
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.errors.txt b/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.errors.txt
new file mode 100644
index 00000000000..07282cd1350
--- /dev/null
+++ b/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/a.ts(2,14): error TS6131: Cannot compile modules using option 'outFile' unless the '--module' flag is 'amd' or 'system'.
+
+
+==== tests/cases/compiler/a.ts (1 errors) ====
+    
+    export class A { } // module
+                 ~
+!!! error TS6131: Cannot compile modules using option 'outFile' unless the '--module' flag is 'amd' or 'system'.
+    
+==== tests/cases/compiler/b.ts (0 errors) ====
+    var x = 0; // global
\ No newline at end of file
diff --git a/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.js b/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.js
new file mode 100644
index 00000000000..48548400f7f
--- /dev/null
+++ b/tests/baselines/reference/outModuleConcatUnspecifiedModuleKind.js
@@ -0,0 +1,11 @@
+//// [tests/cases/compiler/outModuleConcatUnspecifiedModuleKind.ts] ////
+
+//// [a.ts]
+
+export class A { } // module
+
+//// [b.ts]
+var x = 0; // global
+
+//// [out.js]
+var x = 0; // global
diff --git a/tests/baselines/reference/pathsValidation1.errors.txt b/tests/baselines/reference/pathsValidation1.errors.txt
index c6193be67ac..a2d7be5f355 100644
--- a/tests/baselines/reference/pathsValidation1.errors.txt
+++ b/tests/baselines/reference/pathsValidation1.errors.txt
@@ -1,6 +1,6 @@
-error TS5063: Substututions for pattern '*' should be an array.
+error TS5063: Substitutions for pattern '*' should be an array.
 
 
-!!! error TS5063: Substututions for pattern '*' should be an array.
+!!! error TS5063: Substitutions for pattern '*' should be an array.
 ==== tests/cases/compiler/a.ts (0 errors) ====
     let x = 1;
\ No newline at end of file
diff --git a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.symbols b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.symbols
index a6aa91e3a56..2596959de9e 100644
--- a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.symbols
+++ b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.symbols
@@ -562,9 +562,9 @@ class ListWrapper {
 >ListWrapper : Symbol(ListWrapper, Decl(staticAnonymousTypeNotReferencingTypeParameter.ts, 38, 1))
 >l : Symbol(l, Decl(staticAnonymousTypeNotReferencingTypeParameter.ts, 113, 43))
 >T : Symbol(T, Decl(staticAnonymousTypeNotReferencingTypeParameter.ts, 113, 16))
->JSON.stringify : Symbol(JSON.stringify, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>JSON.stringify : Symbol(JSON.stringify, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >JSON : Symbol(JSON, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
->stringify : Symbol(JSON.stringify, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>stringify : Symbol(JSON.stringify, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >l : Symbol(l, Decl(staticAnonymousTypeNotReferencingTypeParameter.ts, 113, 43))
 
   static maximum<T>(dit: typeof ListWrapper, list: T[], predicate: (t: T) => number): T {
diff --git a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
index 90148bdbb19..8d35f32707a 100644
--- a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
+++ b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
@@ -662,9 +662,9 @@ class ListWrapper {
 >l : T[]
 >T : T
 >JSON.stringify(l) : string
->JSON.stringify : { (value: any): string; (value: any, replacer: (key: string, value: any) => any): string; (value: any, replacer: any[]): string; (value: any, replacer: (key: string, value: any) => any, space: string | number): string; (value: any, replacer: any[], space: string | number): string; }
+>JSON.stringify : { (value: any, replacer?: (key: string, value: any) => any, space?: string | number): string; (value: any, replacer?: (number | string)[], space?: string | number): string; }
 >JSON : JSON
->stringify : { (value: any): string; (value: any, replacer: (key: string, value: any) => any): string; (value: any, replacer: any[]): string; (value: any, replacer: (key: string, value: any) => any, space: string | number): string; (value: any, replacer: any[], space: string | number): string; }
+>stringify : { (value: any, replacer?: (key: string, value: any) => any, space?: string | number): string; (value: any, replacer?: (number | string)[], space?: string | number): string; }
 >l : T[]
 
   static maximum<T>(dit: typeof ListWrapper, list: T[], predicate: (t: T) => number): T {
diff --git a/tests/baselines/reference/typeReferenceDirectives11.errors.txt b/tests/baselines/reference/typeReferenceDirectives11.errors.txt
new file mode 100644
index 00000000000..45433bf3b83
--- /dev/null
+++ b/tests/baselines/reference/typeReferenceDirectives11.errors.txt
@@ -0,0 +1,18 @@
+/mod1.ts(2,17): error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
+
+
+==== /mod2.ts (0 errors) ====
+    
+    import {foo} from "./mod1";
+    export const bar = foo();
+==== /types/lib/index.d.ts (0 errors) ====
+    
+    
+    interface Lib { x }
+    
+==== /mod1.ts (1 errors) ====
+    
+    export function foo(): Lib { return {x: 1} }
+                    ~~~
+!!! error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/typeReferenceDirectives11.symbols b/tests/baselines/reference/typeReferenceDirectives11.symbols
deleted file mode 100644
index 875bb2a0900..00000000000
--- a/tests/baselines/reference/typeReferenceDirectives11.symbols
+++ /dev/null
@@ -1,23 +0,0 @@
-=== /mod2.ts ===
-
-import {foo} from "./mod1";
->foo : Symbol(foo, Decl(mod2.ts, 1, 8))
-
-export const bar = foo();
->bar : Symbol(bar, Decl(mod2.ts, 2, 12))
->foo : Symbol(foo, Decl(mod2.ts, 1, 8))
-
-=== /types/lib/index.d.ts ===
-
-
-interface Lib { x }
->Lib : Symbol(Lib, Decl(index.d.ts, 0, 0))
->x : Symbol(Lib.x, Decl(index.d.ts, 2, 15))
-
-=== /mod1.ts ===
-
-export function foo(): Lib { return {x: 1} }
->foo : Symbol(foo, Decl(mod1.ts, 0, 0))
->Lib : Symbol(Lib, Decl(index.d.ts, 0, 0))
->x : Symbol(x, Decl(mod1.ts, 1, 37))
-
diff --git a/tests/baselines/reference/typeReferenceDirectives11.types b/tests/baselines/reference/typeReferenceDirectives11.types
deleted file mode 100644
index 93d80b7988a..00000000000
--- a/tests/baselines/reference/typeReferenceDirectives11.types
+++ /dev/null
@@ -1,26 +0,0 @@
-=== /mod2.ts ===
-
-import {foo} from "./mod1";
->foo : () => Lib
-
-export const bar = foo();
->bar : Lib
->foo() : Lib
->foo : () => Lib
-
-=== /types/lib/index.d.ts ===
-
-
-interface Lib { x }
->Lib : Lib
->x : any
-
-=== /mod1.ts ===
-
-export function foo(): Lib { return {x: 1} }
->foo : () => Lib
->Lib : Lib
->{x: 1} : { x: number; }
->x : number
->1 : number
-
diff --git a/tests/baselines/reference/typeReferenceDirectives12.errors.txt b/tests/baselines/reference/typeReferenceDirectives12.errors.txt
new file mode 100644
index 00000000000..c1b3a6126b2
--- /dev/null
+++ b/tests/baselines/reference/typeReferenceDirectives12.errors.txt
@@ -0,0 +1,37 @@
+/main.ts(1,14): error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
+
+
+==== /mod2.ts (0 errors) ====
+    import { Cls } from "./main";
+    import "./mod1";
+    
+    export const cls = Cls;
+    export const foo = new Cls().foo();
+    export const bar = Cls.bar();
+==== /types/lib/index.d.ts (0 errors) ====
+    
+    
+    interface Lib { x }
+    
+==== /main.ts (1 errors) ====
+    export class Cls {
+                 ~~~
+!!! error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
+        x
+    }
+    
+==== /mod1.ts (0 errors) ====
+    /// <reference types="lib" />
+    
+    import {Cls} from "./main";
+    Cls.prototype.foo = function() { return undefined; }
+    
+    declare module "./main" {
+        interface Cls {
+            foo(): Lib;
+        }
+        namespace Cls {
+            function bar(): Lib;
+        }
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/typeReferenceDirectives12.symbols b/tests/baselines/reference/typeReferenceDirectives12.symbols
deleted file mode 100644
index 30b24c39284..00000000000
--- a/tests/baselines/reference/typeReferenceDirectives12.symbols
+++ /dev/null
@@ -1,68 +0,0 @@
-=== /mod2.ts ===
-import { Cls } from "./main";
->Cls : Symbol(Cls, Decl(mod2.ts, 0, 8))
-
-import "./mod1";
-
-export const cls = Cls;
->cls : Symbol(cls, Decl(mod2.ts, 3, 12))
->Cls : Symbol(Cls, Decl(mod2.ts, 0, 8))
-
-export const foo = new Cls().foo();
->foo : Symbol(foo, Decl(mod2.ts, 4, 12))
->new Cls().foo : Symbol(Cls.foo, Decl(mod1.ts, 6, 19))
->Cls : Symbol(Cls, Decl(mod2.ts, 0, 8))
->foo : Symbol(Cls.foo, Decl(mod1.ts, 6, 19))
-
-export const bar = Cls.bar();
->bar : Symbol(bar, Decl(mod2.ts, 5, 12))
->Cls.bar : Symbol(Cls.bar, Decl(mod1.ts, 9, 19))
->Cls : Symbol(Cls, Decl(mod2.ts, 0, 8))
->bar : Symbol(Cls.bar, Decl(mod1.ts, 9, 19))
-
-=== /types/lib/index.d.ts ===
-
-
-interface Lib { x }
->Lib : Symbol(Lib, Decl(index.d.ts, 0, 0))
->x : Symbol(Lib.x, Decl(index.d.ts, 2, 15))
-
-=== /main.ts ===
-export class Cls {
->Cls : Symbol(Cls, Decl(main.ts, 0, 0), Decl(mod1.ts, 5, 25), Decl(mod1.ts, 8, 5))
-
-    x
->x : Symbol(Cls.x, Decl(main.ts, 0, 18))
-}
-
-=== /mod1.ts ===
-/// <reference types="lib" />
-
-import {Cls} from "./main";
->Cls : Symbol(Cls, Decl(mod1.ts, 2, 8))
-
-Cls.prototype.foo = function() { return undefined; }
->Cls.prototype.foo : Symbol(Cls.foo, Decl(mod1.ts, 6, 19))
->Cls.prototype : Symbol(Cls.prototype)
->Cls : Symbol(Cls, Decl(mod1.ts, 2, 8))
->prototype : Symbol(Cls.prototype)
->foo : Symbol(Cls.foo, Decl(mod1.ts, 6, 19))
->undefined : Symbol(undefined)
-
-declare module "./main" {
-    interface Cls {
->Cls : Symbol(Cls, Decl(main.ts, 0, 0), Decl(mod1.ts, 5, 25), Decl(mod1.ts, 8, 5))
-
-        foo(): Lib;
->foo : Symbol(Cls.foo, Decl(mod1.ts, 6, 19))
->Lib : Symbol(Lib, Decl(index.d.ts, 0, 0))
-    }
-    namespace Cls {
->Cls : Symbol(Cls, Decl(main.ts, 0, 0), Decl(mod1.ts, 5, 25), Decl(mod1.ts, 8, 5))
-
-        function bar(): Lib;
->bar : Symbol(bar, Decl(mod1.ts, 9, 19))
->Lib : Symbol(Lib, Decl(index.d.ts, 0, 0))
-    }
-}
-
diff --git a/tests/baselines/reference/typeReferenceDirectives12.types b/tests/baselines/reference/typeReferenceDirectives12.types
deleted file mode 100644
index bd429b91f1c..00000000000
--- a/tests/baselines/reference/typeReferenceDirectives12.types
+++ /dev/null
@@ -1,73 +0,0 @@
-=== /mod2.ts ===
-import { Cls } from "./main";
->Cls : typeof Cls
-
-import "./mod1";
-
-export const cls = Cls;
->cls : typeof Cls
->Cls : typeof Cls
-
-export const foo = new Cls().foo();
->foo : Lib
->new Cls().foo() : Lib
->new Cls().foo : () => Lib
->new Cls() : Cls
->Cls : typeof Cls
->foo : () => Lib
-
-export const bar = Cls.bar();
->bar : Lib
->Cls.bar() : Lib
->Cls.bar : () => Lib
->Cls : typeof Cls
->bar : () => Lib
-
-=== /types/lib/index.d.ts ===
-
-
-interface Lib { x }
->Lib : Lib
->x : any
-
-=== /main.ts ===
-export class Cls {
->Cls : Cls
-
-    x
->x : any
-}
-
-=== /mod1.ts ===
-/// <reference types="lib" />
-
-import {Cls} from "./main";
->Cls : typeof Cls
-
-Cls.prototype.foo = function() { return undefined; }
->Cls.prototype.foo = function() { return undefined; } : () => any
->Cls.prototype.foo : () => Lib
->Cls.prototype : Cls
->Cls : typeof Cls
->prototype : Cls
->foo : () => Lib
->function() { return undefined; } : () => any
->undefined : undefined
-
-declare module "./main" {
-    interface Cls {
->Cls : Cls
-
-        foo(): Lib;
->foo : () => Lib
->Lib : Lib
-    }
-    namespace Cls {
->Cls : typeof Cls
-
-        function bar(): Lib;
->bar : () => Lib
->Lib : Lib
-    }
-}
-
diff --git a/tests/cases/compiler/outModuleConcatUnspecifiedModuleKind.ts b/tests/cases/compiler/outModuleConcatUnspecifiedModuleKind.ts
new file mode 100644
index 00000000000..976a47e2f78
--- /dev/null
+++ b/tests/cases/compiler/outModuleConcatUnspecifiedModuleKind.ts
@@ -0,0 +1,8 @@
+// @target: ES5
+// @outFile: out.js
+
+// @Filename: a.ts
+export class A { } // module
+
+// @Filename: b.ts
+var x = 0; // global
\ No newline at end of file