diff --git a/.travis.yml b/.travis.yml
index 50ff61e20f4..305fad1e4a7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,7 @@ node_js:
 
 sudo: false
 
-before_script: 
-  - npm install -g codeclimate-test-reporter
+before_script: npm install -g codeclimate-test-reporter
 
 after_script:
   - cat coverage/lcov.info | codeclimate
diff --git a/Jakefile b/Jakefile
index 4c971efe0c9..324356a4af5 100644
--- a/Jakefile
+++ b/Jakefile
@@ -3,6 +3,7 @@
 var fs = require("fs");
 var os = require("os");
 var path = require("path");
+var child_process = require("child_process");
 
 // Variables
 var compilerDirectory = "src/compiler/";
@@ -25,8 +26,7 @@ var thirdParty = "ThirdPartyNoticeText.txt";
 var nodeModulesPathPrefix = path.resolve("./node_modules/.bin/") + path.delimiter;
 if (process.env.path !== undefined) {
    process.env.path = nodeModulesPathPrefix + process.env.path;
-} 
-else if (process.env.PATH !== undefined) {
+} else if (process.env.PATH !== undefined) {
    process.env.PATH = nodeModulesPathPrefix + process.env.PATH;
 }
 
@@ -203,8 +203,7 @@ function concatenateFiles(destinationFile, sourceFiles) {
 var useDebugMode = true;
 var host = (process.env.host || process.env.TYPESCRIPT_HOST || "node");
 var compilerFilename = "tsc.js";
-
-   /* Compiles a file from a list of sources
+/* Compiles a file from a list of sources
     * @param outFile: the target file name
     * @param sources: an array of the names of the source files
     * @param prereqs: prerequisite tasks to compiling the file
@@ -215,9 +214,8 @@ var compilerFilename = "tsc.js";
     * @param outDir: true to compile using --outDir
     * @param keepComments: false to compile using --removeComments
     * @param callback: a function to execute after the compilation process ends
-    * @async
     */
-    function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOutFile, generateDeclarations, outDir, preserveConstEnums, keepComments, noResolve, stripInternal, callback) {
+function compileFile(outFile, sources, prereqs, prefixes, useBuiltCompiler, noOutFile, generateDeclarations, outDir, preserveConstEnums, keepComments, noResolve, stripInternal, callback) {
     file(outFile, prereqs, function() {
         var dir = useBuiltCompiler ? builtLocalDirectory : LKGDirectory;
         var options = "--module commonjs -noImplicitAny";
@@ -256,9 +254,17 @@ var compilerFilename = "tsc.js";
 
         var cmd = host + " " + dir + compilerFilename + " " + options + " ";
         cmd = cmd + sources.join(" ");
+        console.log(cmd + "\n");
 
-        exec(cmd, function() {
-            console.log("")
+        var ex = jake.createExec([cmd]);
+        // Add listeners for output and error
+        ex.addListener("stdout", function(output) {
+            process.stdout.write(output);
+        });
+        ex.addListener("stderr", function(error) {
+            process.stderr.write(error);
+        });
+        ex.addListener("cmdEnd", function() {
             if (!useDebugMode && prefixes && fs.existsSync(outFile)) {
                 for (var i in prefixes) {
                     prependFile(prefixes[i], outFile);
@@ -268,14 +274,14 @@ var compilerFilename = "tsc.js";
             if (callback) {
                 callback();
             }
-            else {
-                complete();
-            }
-        }, /* errorHandler */ function() {
+
+            complete();
+        });
+        ex.addListener("error", function() {
             fs.unlinkSync(outFile);
             fail("Compilation of " + outFile + " unsuccessful");
         });
-
+        ex.run();
     }, {async: true});
 }
 
@@ -318,8 +324,19 @@ compileFile(processDiagnosticMessagesJs,
 // The generated diagnostics map; built for the compiler and for the 'generate-diagnostics' task
 file(diagnosticInfoMapTs, [processDiagnosticMessagesJs, diagnosticMessagesJson], function () {
     var cmd = "node " + processDiagnosticMessagesJs + " "  + diagnosticMessagesJson;
-
-    exec(cmd);
+    console.log(cmd);
+    var ex = jake.createExec([cmd]);
+    // Add listeners for output and error
+    ex.addListener("stdout", function(output) {
+        process.stdout.write(output);
+    });
+    ex.addListener("stderr", function(error) {
+        process.stderr.write(error);
+    });
+    ex.addListener("cmdEnd", function() {
+        complete();
+    });
+    ex.run();
 }, {async: true})
 
 desc("Generates a diagnostic file in TypeScript based on an input JSON file");
@@ -384,7 +401,6 @@ compileFile(nodeDefinitionsFile, servicesSources,[builtLocalDirectory, copyright
 
                 // Delete the temp dir
                 jake.rmRf(tempDirPath, {silent: true});
-                complete();
            });
 
 var serverFile = path.join(builtLocalDirectory, "tsserver.js");
@@ -433,8 +449,10 @@ compileFile(word2mdJs,
 file(specMd, [word2mdJs, specWord], function () {
     var specWordFullPath = path.resolve(specWord);
     var cmd = "cscript //nologo " + word2mdJs + ' "' + specWordFullPath + '" ' + specMd;
-
-    exec(cmd);
+    console.log(cmd);
+    child_process.exec(cmd, function () {
+        complete();
+    });
 }, {async: true})
 
 
@@ -485,24 +503,22 @@ var refTest262Baseline = path.join(internalTests, "baselines/test262/reference")
 desc("Builds the test infrastructure using the built compiler");
 task("tests", ["local", run].concat(libraryTargets));
 
-/* Executes a command
- * @param cmd: command to execute
- * @param completeHandler?: a function to execute after the command ends
- * @param errorHandler?: a function to execute if an error occurs
- * @async
- */
-function exec(cmd, completeHandler, errorHandler) {
-    console.log(cmd);
-    var ex = jake.createExec([cmd], {windowsVerbatimArguments: true, interactive: true});
+function exec(cmd, completeHandler) {
+    var ex = jake.createExec([cmd], {windowsVerbatimArguments: true});
+    // Add listeners for output and error
+    ex.addListener("stdout", function(output) {
+        process.stdout.write(output);
+    });
+    ex.addListener("stderr", function(error) {
+        process.stderr.write(error);
+    });
     ex.addListener("cmdEnd", function() {
         if (completeHandler) {
             completeHandler();
         }
-        else {
-            complete();
-        }
+        complete();
     });
-    ex.addListener("error", errorHandler || function(e, status) {
+    ex.addListener("error", function(e, status) {
         fail("Process exited with code " + status);
     })
 
@@ -521,7 +537,7 @@ function cleanTestDirs() {
     }
 
     jake.mkdirP(localRwcBaseline);
-    jake.mkdirP(localTest262Baseline);
+	jake.mkdirP(localTest262Baseline);
     jake.mkdirP(localBaseline);
 }
 
@@ -532,14 +548,10 @@ function writeTestConfigFile(tests, testConfigFile) {
     fs.writeFileSync('test.config', testConfigContents);
 }
 
-/* Removes project output
- * @async
- */
 function deleteTemporaryProjectOutput() {
     if (fs.existsSync(path.join(localBaseline, "projectOutput/"))) {
         jake.rmRf(path.join(localBaseline, "projectOutput/"));
     }
-    complete();
 }
 
 var testTimeout = 20000;
@@ -568,14 +580,14 @@ task("runtests", ["tests", builtLocalDirectory], function() {
     // timeout normally isn't necessary but Travis-CI has been timing out on compiler baselines occasionally
     // default timeout is 2sec which really should be enough, but maybe we just need a small amount longer
     var cmd = host + " -R " + reporter + tests + colors + ' -t ' + testTimeout + ' ' + run;
-
+    console.log(cmd);
     exec(cmd, deleteTemporaryProjectOutput);
 }, {async: true});
 
 desc("Generates code coverage data via instanbul")
 task("generate-code-coverage", ["tests", builtLocalDirectory], function () {
     var cmd = 'istanbul cover node_modules/mocha/bin/_mocha -- -R min -t ' + testTimeout + ' ' + run;
-
+    console.log(cmd);
     exec(cmd);
 }, { async: true });
 
@@ -607,6 +619,7 @@ task("runtests-browser", ["tests", "browserify", builtLocalDirectory], function(
 
     tests = tests ? tests : '';
     var cmd = host + " tests/webTestServer.js " + port + " " + browser + " " + tests
+    console.log(cmd);
     exec(cmd);
 }, {async: true});
 
@@ -622,12 +635,14 @@ function getDiffTool() {
 desc("Diffs the compiler baselines using the diff tool specified by the 'DIFF' environment variable");
 task('diff', function () {
     var cmd = '"' +  getDiffTool()  + '" ' + refBaseline + ' ' + localBaseline;
+    console.log(cmd)
     exec(cmd);
 }, {async: true});
 
 desc("Diffs the RWC baselines using the diff tool specified by the 'DIFF' environment variable");
 task('diff-rwc', function () {
     var cmd = '"' +  getDiffTool()  + '" ' + refRwcBaseline + ' ' + localRwcBaseline;
+    console.log(cmd)
     exec(cmd);
 }, {async: true});
 
@@ -674,6 +689,13 @@ task("webhost", [webhostJsPath], function() {
     jake.cpR(path.join(builtLocalDirectory, "lib.d.ts"), "tests/webhost/", {silent: true});
 });
 
+// Perf compiler
+var perftscPath = "tests/perftsc.ts";
+var perftscJsPath = "built/local/perftsc.js";
+compileFile(perftscJsPath, [perftscPath], [tscFile, perftscPath, "tests/perfsys.ts"].concat(libraryTargets), [], /*useBuiltCompiler*/ true);
+desc("Builds augmented version of the compiler for perf tests");
+task("perftsc", [perftscJsPath]);
+
 // Instrumented compiler
 var loggedIOpath = harnessDirectory + 'loggedIO.ts';
 var loggedIOJsPath = builtLocalDirectory + 'loggedIO.js';
@@ -682,12 +704,14 @@ file(loggedIOJsPath, [builtLocalDirectory, loggedIOpath], function() {
     jake.mkdirP(temp);
     var options = "--outdir " + temp + ' ' + loggedIOpath;
     var cmd = host + " " + LKGDirectory + compilerFilename + " " + options + " ";
-
-    exec(cmd, function() {
+    console.log(cmd + "\n");
+    var ex = jake.createExec([cmd]);
+    ex.addListener("cmdEnd", function() {
         fs.renameSync(temp + '/harness/loggedIO.js', loggedIOJsPath);
         jake.rmRf(temp);
         complete();
     });
+    ex.run();
 }, {async: true});
 
 var instrumenterPath = harnessDirectory + 'instrumenter.ts';
@@ -697,6 +721,10 @@ compileFile(instrumenterJsPath, [instrumenterPath], [tscFile, instrumenterPath],
 desc("Builds an instrumented tsc.js");
 task('tsc-instrumented', [loggedIOJsPath, instrumenterJsPath, tscFile], function() {
     var cmd = host + ' ' + instrumenterJsPath + ' record iocapture ' + builtLocalDirectory + compilerFilename;
-
-    exec(cmd);
+    console.log(cmd);
+    var ex = jake.createExec([cmd]);
+    ex.addListener("cmdEnd", function() {
+        complete();
+    });
+    ex.run();
 }, { async: true });
diff --git a/package.json b/package.json
index b53916b37b3..9261174b68f 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,6 @@
         "codeclimate-test-reporter": "latest"
     },
     "scripts": {
-        "test": "jake --trace generate-code-coverage"
+        "test": "jake generate-code-coverage"
     }
 }
diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index 68507b34574..57c2298d3d3 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -258,7 +258,7 @@ module ts {
             reportDiagnostic(createCompilerDiagnostic(Diagnostics.Compilation_complete_Watching_for_file_changes));
         }
 
-        function getSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void) {
+        function getSourceFile(fileName: string, languageVersion: ScriptTarget, onError ?: (message: string) => void) {
             // Return existing SourceFile object if one is available
             if (cachedProgram) {
                 var sourceFile = cachedProgram.getSourceFile(fileName);
diff --git a/tests/perfsys.ts b/tests/perfsys.ts
new file mode 100644
index 00000000000..143d0d637d4
--- /dev/null
+++ b/tests/perfsys.ts
@@ -0,0 +1,105 @@
+/// <reference path="..\src\compiler\sys.ts"/>
+/// <reference path="..\src\compiler\types.ts"/>
+
+module perftest {
+
+    interface IOLog {
+        resolvePath: ts.Map<string>;
+        fileNames: string[];
+    }
+
+    export interface IO {
+        getOut(): string;
+    }
+
+    export var readFile = ts.sys.readFile;
+    var writeFile = ts.sys.writeFile;
+    export var write = ts.sys.write;
+    var resolvePath = ts.sys.resolvePath;
+    export var getExecutingFilePath = ts.sys.getExecutingFilePath;
+    export var getCurrentDirectory = ts.sys.getCurrentDirectory;
+    var exit = ts.sys.exit;
+
+    var args = ts.sys.args;
+
+    // augment sys so first ts.executeCommandLine call will be finish silently
+    ts.sys.write = (s: string) => { };
+    ts.sys.exit = (code: number) => { };
+    ts.sys.args = []
+
+    export function restoreSys() {
+        ts.sys.args = args;
+        ts.sys.write = write;
+    }
+
+    export function hasLogIOFlag() {
+        return args.length > 2 && args[0] === "--logio";
+    }
+
+    export function getArgsWithoutLogIOFlag() {
+        return args.slice(2);
+    }
+
+    export function getArgsWithoutIOLogFile() {
+        return args.slice(1);
+    }
+
+    var resolvePathLog: ts.Map<string> = {};
+    
+    export function interceptIO() {
+        ts.sys.resolvePath = (s) => {
+            var result = resolvePath(s);
+            resolvePathLog[s] = result;
+            return result;
+        };
+    }
+
+    export function writeIOLog(fileNames: string[]) {
+        var path = args[1];
+        var log: IOLog = {
+            fileNames: fileNames,
+            resolvePath: resolvePathLog
+        };
+
+        writeFile(path, JSON.stringify(log));
+    }
+
+    export function prepare(): IO {
+        var log = <IOLog>JSON.parse(readFile(args[0]));
+
+        var files: ts.Map<string> = {};
+        log.fileNames.forEach(f => { files[f] = readFile(f); })
+        
+        ts.sys.createDirectory = (s: string) => { };
+        ts.sys.directoryExists = (s: string) => true;
+        ts.sys.fileExists = (s: string) => true;
+
+        var currentDirectory = ts.sys.getCurrentDirectory();
+        ts.sys.getCurrentDirectory = () => currentDirectory;
+
+        var executingFilePath = ts.sys.getExecutingFilePath();
+        ts.sys.getExecutingFilePath = () => executingFilePath;
+
+        ts.sys.readFile = (s: string) => {
+            return files[s];
+        }
+
+        ts.sys.resolvePath = (s: string) => {
+            var path = log.resolvePath[s];
+            if (!path) {
+                throw new Error("Unexpected path '" + s + "'");
+            }
+            return path
+        }
+
+        ts.sys.writeFile = (path: string, data: string) => { };
+
+        var out: string = "";
+
+        ts.sys.write = (s: string) => { out += s; };
+
+        return {
+            getOut: () => out,
+        };
+    }
+}
diff --git a/tests/perftsc.ts b/tests/perftsc.ts
new file mode 100644
index 00000000000..e0189896a15
--- /dev/null
+++ b/tests/perftsc.ts
@@ -0,0 +1,30 @@
+/// <reference path="perfsys.ts"/>
+/// <reference path="..\src\compiler\tsc.ts"/>
+
+// resolve all files used in this compilation
+if (perftest.hasLogIOFlag()) {
+    perftest.interceptIO();
+
+    var compilerHost: ts.CompilerHost = {
+        getSourceFile: (s, v) => {
+            var content = perftest.readFile(s);
+            return content !== undefined ? ts.createSourceFile(s, content, v) : undefined;
+        },
+        getDefaultLibFilename: () => ts.combinePaths(ts.getDirectoryPath(ts.normalizePath(perftest.getExecutingFilePath())), "lib.d.ts"),
+        writeFile: (f: string, content: string) => { throw new Error("Unexpected operation: writeFile"); },
+        getCurrentDirectory: () => perftest.getCurrentDirectory(),
+        getCanonicalFileName: (f: string) => ts.sys.useCaseSensitiveFileNames ? f : f.toLowerCase(),
+        useCaseSensitiveFileNames: () => ts.sys.useCaseSensitiveFileNames,
+        getNewLine: () => ts.sys.newLine
+    };
+
+    var commandLine = ts.parseCommandLine(perftest.getArgsWithoutLogIOFlag());
+    var program = ts.createProgram(commandLine.filenames, commandLine.options, compilerHost);
+    var fileNames = program.getSourceFiles().map(f => f.filename);
+    perftest.writeIOLog(fileNames);
+}
+else {
+    var io = perftest.prepare();
+    ts.executeCommandLine(perftest.getArgsWithoutIOLogFile());
+    perftest.write(io.getOut());
+}