diff --git a/gulpfile.js b/gulpfile.js
index 6cf2da365..fe2a0b90f 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -29,6 +29,7 @@ module.exports = {
   buildLangfiles: buildTasks.langfiles,
   buildCompiled: buildTasks.compiled,
   buildAdvancedCompilationTest: buildTasks.advancedCompilationTest,
+  buildTs: buildTasks.buildTypescript,
   // TODO(5621): Re-enable once typings generation is fixed.
   // checkin: gulp.parallel(buildTasks.checkinBuilt, typings.checkinTypings),
   checkin: gulp.parallel(buildTasks.checkinBuilt),
diff --git a/package.json b/package.json
index 42fee0197..101863a0a 100644
--- a/package.json
+++ b/package.json
@@ -26,6 +26,7 @@
     "build:compressed": "npm run build:compiled",
     "build:deps": "gulp buildDeps",
     "build:langfiles": "gulp buildLangfiles",
+    "build-ts": "gulp buildTs && gulp build --compileTs",
     "bump": "npm --no-git-tag-version version 4.$(date +'%Y%m%d').0",
     "clean": "gulp clean",
     "clean:build": "gulp cleanBuildDir",
diff --git a/scripts/gulpfiles/build_tasks.js b/scripts/gulpfiles/build_tasks.js
index aeec016fb..0748ea118 100644
--- a/scripts/gulpfiles/build_tasks.js
+++ b/scripts/gulpfiles/build_tasks.js
@@ -25,7 +25,7 @@ var closureDeps = require('google-closure-deps');
 var argv = require('yargs').argv;
 var rimraf = require('rimraf');
 
-var {BUILD_DIR} = require('./config');
+var {BUILD_DIR, TSC_OUTPUT_DIR} = require('./config');
 var {getPackageJson} = require('./helper_tasks');
 
 ////////////////////////////////////////////////////////////
@@ -89,7 +89,7 @@ const NAMESPACE_OBJECT = '$';
  * The function getChunkOptions will, after running
  * closure-calculate-chunks, update each chunk to add the following
  * properties:
- * 
+ *
  * - .dependencies: a list of the chunks the chunk depends upon.
  * - .wrapper: the chunk wrapper.
  *
@@ -104,28 +104,34 @@ const chunks = [
     factoryPreamble: `const ${NAMESPACE_OBJECT}={};`,
     factoryPostamble:
         `${NAMESPACE_OBJECT}.Blockly.internal_=${NAMESPACE_OBJECT};`,
-  }, {
+  },
+  {
     name: 'blocks',
     entry: 'blocks/all.js',
     exports: 'Blockly.Blocks',
     importAs: 'BlocklyBlocks',
-  }, {
+  },
+  {
     name: 'javascript',
     entry: 'generators/javascript/all.js',
     exports: 'Blockly.JavaScript',
-  }, {
+  },
+  {
     name: 'python',
     entry: 'generators/python/all.js',
     exports: 'Blockly.Python',
-  }, {
+  },
+  {
     name: 'php',
     entry: 'generators/php/all.js',
     exports: 'Blockly.PHP',
-  }, {
+  },
+  {
     name: 'lua',
     entry: 'generators/lua/all.js',
     exports: 'Blockly.Lua',
-  }, {
+  },
+  {
     name: 'dart',
     entry: 'generators/dart/all.js',
     exports: 'Blockly.Dart',
@@ -224,9 +230,10 @@ function buildDeps(done) {
       'node_modules/google-closure-library/closure/goog' :
       'closure/goog';
 
+  const coreDir = argv.compileTs ? path.join(TSC_OUTPUT_DIR, 'core') : 'core';
   const roots = [
     closurePath,
-    'core',
+    coreDir,
     'blocks',
     'generators',
   ];
@@ -350,6 +357,9 @@ return ${NAMESPACE_OBJECT}.${chunk.exports};
  * TODO(cpcallen): maybeAddClosureLibrary?  Or maybe remove base.js?
  */
 function getChunkOptions() {
+  if (argv.compileTs) {
+    chunks[0].entry = path.join(TSC_OUTPUT_DIR, chunks[0].entry);
+  }
   const cccArgs = [
     '--closure-library-base-js-path ./closure/goog/base_minimal.js',
     '--deps-file ./tests/deps.js',
@@ -432,12 +442,12 @@ function getChunkOptions() {
   return {chunk: chunkList, js: rawOptions.js, chunk_wrapper: chunkWrappers};
 }
 
-/** 
+/**
  * RegExp that globally matches path.sep (i.e., "/" or "\").
  */
 const pathSepRegExp = new RegExp(path.sep.replace(/\\/, '\\\\'), "g");
 
-/** 
+/**
  * Modify the supplied gulp.rename path object to relax @package
  * restrictions in core/.
  *
@@ -457,10 +467,11 @@ const pathSepRegExp = new RegExp(path.sep.replace(/\\/, '\\\\'), "g");
  */
 function flattenCorePaths(pathObject) {
   const dirs = pathObject.dirname.split(path.sep);
-  if (dirs[0] === 'core') {
-    pathObject.dirname = dirs[0];
+  const coreIndex = argv.compileTs ? 2 : 0;
+  if (dirs[coreIndex] === 'core') {
+    pathObject.dirname = path.join(...dirs.slice(0, coreIndex + 1));
     pathObject.basename =
-        dirs.slice(1).concat(pathObject.basename).join('-slash-');
+        dirs.slice(coreIndex + 1).concat(pathObject.basename).join('-slash-');
   }
 }
 
@@ -503,7 +514,7 @@ function compile(options) {
 }
 
 /**
- * This task compiles the core library, blocks and generators, creating 
+ * This task compiles the core library, blocks and generators, creating
  * blockly_compressed.js, blocks_compressed.js, etc.
  *
  * The deps.js file must be up-to-date.
@@ -540,10 +551,15 @@ function buildCompiled() {
  * closure compiler's ADVANCED_COMPILATION mode.
  */
 function buildAdvancedCompilationTest() {
+  const coreSrcs = argv.compileTs ?
+      TSC_OUTPUT_DIR + '/core/**/*.js' : 'core/**/*.js';
   const srcs = [
     'closure/goog/base_minimal.js',
-    'core/**/*.js', 'blocks/**/*.js', 'generators/**/*.js',
-    'tests/compile/main.js', 'tests/compile/test_blocks.js',
+    coreSrcs,
+    'blocks/**/*.js',
+    'generators/**/*.js',
+    'tests/compile/main.js',
+    'tests/compile/test_blocks.js',
   ];
 
   // Closure Compiler options.
@@ -615,6 +631,11 @@ function format() {
       .pipe(gulp.dest('.'));
 };
 
+function buildTypescript(done) {
+  execSync('npx tsc', {stdio: 'inherit'});
+  done();
+}
+
 module.exports = {
   build: build,
   deps: buildDeps,
@@ -625,4 +646,5 @@ module.exports = {
   checkinBuilt: checkinBuilt,
   cleanBuildDir: cleanBuildDir,
   advancedCompilationTest: buildAdvancedCompilationTest,
+  buildTypescript: buildTypescript
 }
diff --git a/scripts/gulpfiles/config.js b/scripts/gulpfiles/config.js
index c9eb518ca..f8ee8c1a8 100644
--- a/scripts/gulpfiles/config.js
+++ b/scripts/gulpfiles/config.js
@@ -15,7 +15,7 @@ var path = require('path');
 //
 // TODO(#5007): If you modify these values, you must also modify the
 // corresponding values in the following files:
-// 
+//
 // - tests/scripts/compile_typings.sh
 // - tests/scripts/check_metadata.sh
 module.exports = {
@@ -28,4 +28,8 @@ module.exports = {
 
   // Directory to write typings output to.
   TYPINGS_BUILD_DIR: path.join('build', 'typings'),
+
+  // Directory where typescript compiler output can be found.
+  // Matches the value in tsconfig.json: outDir
+  TSC_OUTPUT_DIR: path.join('build', 'ts'),
 };
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 000000000..88c95700b
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,25 @@
+{
+  "include": [
+    "core/**/*",
+    "closure/goog/base_minimal.js",
+  ],
+  "compilerOptions": {
+    // Tells TypeScript to read JS files, as
+    // normally they are ignored as source files
+    "allowJs": true,
+
+    // Enable the next few options for type declarations.
+    // Generate d.ts files
+    //"declaration": true,
+    // Types should go into this directory.
+    // Removing this would place the .d.ts files
+    // next to the .js files
+    //"declarationDir": "build/ts/declarations",
+
+    "outDir": "build/ts",
+    "module": "ES2015",
+    "moduleResolution": "node",
+    "target": "ES2020",
+    "strict": true,
+  }
+}