diff --git a/.gitmodules b/.gitmodules
index bab7f0717a..fc90f02671 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,9 +1,3 @@
-[submodule "v8"]
-	path = v8
-	url = https://chromium.googlesource.com/v8/v8
-[submodule "build"]
-	path = build
-	url = https://github.com/denoland/chromium_build.git
 [submodule "tools/clang"]
 	path = tools/clang
 	url = https://chromium.googlesource.com/chromium/src/tools/clang.git
@@ -22,3 +16,12 @@
 [submodule "third_party/zlib"]
 	path = third_party/zlib
 	url = https://chromium.googlesource.com/chromium/src/third_party/zlib.git
+[submodule "v8"]
+	path = v8
+	url = https://github.com/kishiguro/chromium_v8.git
+[submodule "build"]
+	path = build
+	url = https://github.com/kishiguro/chromium_build.git
+[submodule "third_party/icu"]
+	path = third_party/icu
+	url = https://github.com/kishiguro/icu.git
diff --git a/.gn b/.gn
index b21600ab8d..5c74f7572b 100644
--- a/.gn
+++ b/.gn
@@ -28,7 +28,7 @@ default_args = {
 
   # https://cs.chromium.org/chromium/src/docs/ccache_mac.md
   clang_use_chrome_plugins = false
-  v8_enable_i18n_support = false
+  v8_enable_i18n_support = true
   v8_monolithic = false
   v8_use_external_startup_data = false
   v8_use_snapshot = true
diff --git a/build b/build
index f503a500c8..df0e2bd801 160000
--- a/build
+++ b/build
@@ -1 +1 @@
-Subproject commit f503a500c8d6da6c1fb525d445a431c6ff8a37ed
+Subproject commit df0e2bd8017ac31be8c4797e4d33afe979f8733b
diff --git a/tests/test_api.rs b/tests/test_api.rs
index 5f1a84d299..72f5e531e3 100644
--- a/tests/test_api.rs
+++ b/tests/test_api.rs
@@ -2937,3 +2937,39 @@ fn module_snapshot() {
     }
   }
 }
+
+#[test]
+fn icu_date() {
+  let _setup_guard = setup();
+  let isolate = &mut v8::Isolate::new(Default::default());
+  {
+    let scope = &mut v8::HandleScope::new(isolate);
+    let context = v8::Context::new(scope);
+    let scope = &mut v8::ContextScope::new(scope, context);
+    let source = r#"
+        (new Date(Date.UTC(2020, 5, 26, 7, 0, 0))).toLocaleString("de-DE", {weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' });
+        "#;
+    let value = eval(scope, source).unwrap();
+    let date_de_val = v8::String::new(scope, "Freitag, 26. Juni 2020").unwrap();
+    assert!(value.is_string());
+    assert!(value.strict_equals(date_de_val.into()));
+  }
+}
+
+#[test]
+fn icu_format() {
+  let _setup_guard = setup();
+  let isolate = &mut v8::Isolate::new(Default::default());
+  {
+    let scope = &mut v8::HandleScope::new(isolate);
+    let context = v8::Context::new(scope);
+    let scope = &mut v8::ContextScope::new(scope, context);
+    let source = r#"
+        new Intl.NumberFormat('ja-JP',{ style: 'currency',currency: 'JPY'}).format(1230000);
+        "#;
+    let value = eval(scope, source).unwrap();
+    let currency_jpy_val = v8::String::new(scope, "￥1,230,000").unwrap();
+    assert!(value.is_string());
+    assert!(value.strict_equals(currency_jpy_val.into()));
+  }
+}
diff --git a/third_party/icu b/third_party/icu
new file mode 160000
index 0000000000..aec8e1ee29
--- /dev/null
+++ b/third_party/icu
@@ -0,0 +1 @@
+Subproject commit aec8e1ee291e3cc620e01560c8f7b60458c3bf3b
diff --git a/v8 b/v8
index fb20b5d83e..54ef28208a 160000
--- a/v8
+++ b/v8
@@ -1 +1 @@
-Subproject commit fb20b5d83e381586c7b16fc7aad554eaa5432416
+Subproject commit 54ef28208aa61eb818fe460c62f7b918d5fc77e3