diff --git a/browser_patches/firefox-beta/BUILD_NUMBER b/browser_patches/firefox-beta/BUILD_NUMBER
index dfb2bc3514..5d63b9cc79 100644
--- a/browser_patches/firefox-beta/BUILD_NUMBER
+++ b/browser_patches/firefox-beta/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1310
-Changed: lushnikov@chromium.org Tue Dec 14 15:56:05 PST 2021
+1311
+Changed: lushnikov@chromium.org Tue Dec 14 23:27:53 PST 2021
diff --git a/browser_patches/firefox-beta/build.sh b/browser_patches/firefox-beta/build.sh
index 81278300db..3c75a2597c 100755
--- a/browser_patches/firefox-beta/build.sh
+++ b/browser_patches/firefox-beta/build.sh
@@ -63,6 +63,8 @@ echo "ac_add_options --disable-backgroundtasks" >> .mozconfig
 if [[ -n $FF_DEBUG_BUILD ]]; then
   echo "ac_add_options --enable-debug" >> .mozconfig
   echo "ac_add_options --enable-debug-symbols" >> .mozconfig
+else
+  echo "ac_add_options --enable-release" >> .mozconfig
 fi
 
 if [[ "$(uname)" == MINGW* || "$(uname)" == "Darwin" ]]; then
@@ -86,7 +88,7 @@ if [[ $1 != "--juggler" ]]; then
   fi
 fi
 
-if [[ $1 == "--full" || $2 == "--full" ]]; then
+if [[ $1 == "--full" || $2 == "--full" || $1 == "--bootstrap" ]]; then
   echo "ac_add_options --enable-bootstrap" >> .mozconfig
   if [[ "$(uname)" == "Darwin" || "$(uname)" == "Linux" ]]; then
     SHELL=/bin/sh ./mach --no-interactive bootstrap --application-choice=browser
@@ -99,13 +101,15 @@ fi
 
 if [[ $1 == "--juggler" ]]; then
   ./mach build faster
+elif [[ $1 == "--bootstrap" ]]; then
+  ./mach configure
 else
   ./mach build
+  if [[ "$(uname)" == "Darwin" ]]; then
+    node "${SCRIPT_FOLDER}"/install-preferences.js "$PWD"/${OBJ_FOLDER}/dist
+  else
+    node "${SCRIPT_FOLDER}"/install-preferences.js "$PWD"/${OBJ_FOLDER}/dist/bin
+  fi
 fi
 
-if [[ "$(uname)" == "Darwin" ]]; then
-  node "${SCRIPT_FOLDER}"/install-preferences.js "$PWD"/${OBJ_FOLDER}/dist
-else
-  node "${SCRIPT_FOLDER}"/install-preferences.js "$PWD"/${OBJ_FOLDER}/dist/bin
-fi
 
diff --git a/browser_patches/firefox-beta/patches/bootstrap.diff b/browser_patches/firefox-beta/patches/bootstrap.diff
index 3600d59b08..a49063c819 100644
--- a/browser_patches/firefox-beta/patches/bootstrap.diff
+++ b/browser_patches/firefox-beta/patches/bootstrap.diff
@@ -1863,7 +1863,7 @@ index b32d426ba38045d14e6f1e79d17e8e6061e78227..df782034e79466fcc251e9a06e99d2e1
    }
  
 diff --git a/js/src/vm/DateTime.cpp b/js/src/vm/DateTime.cpp
-index e8f27fb69691aa6062c860a14ec94660fb9e5189..67715cbbc8257f11927564b45bbc8ee5384f809d 100644
+index e8f27fb69691aa6062c860a14ec94660fb9e5189..83cffc97f12072c24a7ea1bbd7b26ee37d856df3 100644
 --- a/js/src/vm/DateTime.cpp
 +++ b/js/src/vm/DateTime.cpp
 @@ -170,6 +170,11 @@ void js::DateTimeInfo::internalResetTimeZone(ResetTimeZoneMode mode) {
@@ -1903,13 +1903,16 @@ index e8f27fb69691aa6062c860a14ec94660fb9e5189..67715cbbc8257f11927564b45bbc8ee5
  #if JS_HAS_INTL_API
  #  if defined(XP_WIN)
  static bool IsOlsonCompatibleWindowsTimeZoneId(std::string_view tz) {
-@@ -719,9 +738,14 @@ void js::ResyncICUDefaultTimeZone() {
+@@ -719,9 +738,17 @@ void js::ResyncICUDefaultTimeZone() {
  
  void js::DateTimeInfo::internalResyncICUDefaultTimeZone() {
  #if JS_HAS_INTL_API
 +  if (!timeZoneOverride_.empty()) {
 +    mozilla::Span<const char> tzid = mozilla::Span(timeZoneOverride_.data(), timeZoneOverride_.length());
-+    mozilla::intl::TimeZone::SetDefaultTimeZone(tzid);
++    auto result = mozilla::intl::TimeZone::SetDefaultTimeZone(tzid);
++    if (result.isErr()) {
++      fprintf(stderr, "ERROR: failed to setup default time zone\n");
++    }
 +    return;
 +  }
 +
diff --git a/browser_patches/firefox/BUILD_NUMBER b/browser_patches/firefox/BUILD_NUMBER
index 00db6f848a..4000f7197a 100644
--- a/browser_patches/firefox/BUILD_NUMBER
+++ b/browser_patches/firefox/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1310
-Changed: lushnikov@chromium.org Mon 13 Dec 2021 07:00:27 PM PST
+1311
+Changed: lushnikov@chromium.org Tue Dec 14 23:26:10 PST 2021
diff --git a/browser_patches/firefox/build.sh b/browser_patches/firefox/build.sh
index d4e65dc653..5548e96b27 100755
--- a/browser_patches/firefox/build.sh
+++ b/browser_patches/firefox/build.sh
@@ -62,6 +62,9 @@ echo "ac_add_options --disable-backgroundtasks" >> .mozconfig
 
 if [[ -n $FF_DEBUG_BUILD ]]; then
   echo "ac_add_options --enable-debug" >> .mozconfig
+  echo "ac_add_options --enable-debug-symbols" >> .mozconfig
+else
+  echo "ac_add_options --enable-release" >> .mozconfig
 fi
 
 if [[ "$(uname)" == MINGW* || "$(uname)" == "Darwin" ]]; then
@@ -89,25 +92,7 @@ if [[ $1 == "--full" || $2 == "--full" ]]; then
   if [[ "$(uname)" == "Darwin" || "$(uname)" == "Linux" ]]; then
     SHELL=/bin/sh ./mach --no-interactive bootstrap --application-choice=browser
   fi
-  if [[ "$(uname)" == "Darwin" ]]; then
-    HOMEBREW_LLVM="/opt/homebrew/opt/llvm/bin/clang";
-    if [[ ! -f "${HOMEBREW_LLVM}" || $($HOMEBREW_LLVM --version) != *"version 13"* ]]; then
-      echo "ERROR: as of Dec, 2021, building release firefox requires HomeBrew LLVM v13"
-      echo "Please run:"
-      echo
-      echo "    brew install llvm@13"
-      echo
-      exit 1
-    fi
-    echo "CC=${HOMEBREW_LLVM}" >> .mozconfig
-    echo "CXX=${HOMEBREW_LLVM}++" >> .mozconfig
-
-    # Download wasi toolchain if needed
-    if [[ ! -d "$HOME/.mozbuild/sysroot-wasm32-wasi" ]]; then
-      ./mach artifact toolchain --from-build toolchain-sysroot-wasm32-wasi
-      mv ./sysroot-wasm32-wasi ~/.mozbuild/
-    fi
-  elif [[ "$(uname)" == "Linux" ]]; then
+  if [[ "$(uname)" == "Linux" ]]; then
     echo "ac_add_options --enable-bootstrap" >> .mozconfig
   fi
   if [[ ! -z "${WIN32_REDIST_DIR}" ]]; then
@@ -116,6 +101,21 @@ if [[ $1 == "--full" || $2 == "--full" ]]; then
   fi
 fi
 
+if [[ "$(uname)" == "Darwin" ]]; then
+  if [[ ! -d "$HOME/.mozbuild/clang" ]]; then
+    echo "ERROR: build toolchains are not found, specifically \$HOME/.mozbuild/clang is not there!"
+    echo "Since December, 2021, build toolchains have to be predownloaded (see https://github.com/microsoft/playwright/pull/10929)"
+    echo
+    echo "To bootstrap toolchains:"
+    echo "    ./browser_patches/prepare_checkout.sh firefox-beta"
+    echo "    ./browser_patches/build.sh firefox-beta --bootstrap"
+    echo
+    exit 1
+  fi
+  export MOZ_AUTOMATION=1
+  export MOZ_FETCHES_DIR=$HOME/.mozbuild
+fi
+
 if ! [[ -f "$HOME/.mozbuild/_virtualenvs/mach/bin/python" ]]; then
   ./mach create-mach-environment
 fi
diff --git a/browser_patches/firefox/patches/bootstrap.diff b/browser_patches/firefox/patches/bootstrap.diff
index 6cf9452cf9..14107eac52 100644
--- a/browser_patches/firefox/patches/bootstrap.diff
+++ b/browser_patches/firefox/patches/bootstrap.diff
@@ -1871,7 +1871,7 @@ index b32d426ba38045d14e6f1e79d17e8e6061e78227..df782034e79466fcc251e9a06e99d2e1
    }
  
 diff --git a/js/src/vm/DateTime.cpp b/js/src/vm/DateTime.cpp
-index e8f27fb69691aa6062c860a14ec94660fb9e5189..67715cbbc8257f11927564b45bbc8ee5384f809d 100644
+index e8f27fb69691aa6062c860a14ec94660fb9e5189..83cffc97f12072c24a7ea1bbd7b26ee37d856df3 100644
 --- a/js/src/vm/DateTime.cpp
 +++ b/js/src/vm/DateTime.cpp
 @@ -170,6 +170,11 @@ void js::DateTimeInfo::internalResetTimeZone(ResetTimeZoneMode mode) {
@@ -1911,13 +1911,16 @@ index e8f27fb69691aa6062c860a14ec94660fb9e5189..67715cbbc8257f11927564b45bbc8ee5
  #if JS_HAS_INTL_API
  #  if defined(XP_WIN)
  static bool IsOlsonCompatibleWindowsTimeZoneId(std::string_view tz) {
-@@ -719,9 +738,14 @@ void js::ResyncICUDefaultTimeZone() {
+@@ -719,9 +738,17 @@ void js::ResyncICUDefaultTimeZone() {
  
  void js::DateTimeInfo::internalResyncICUDefaultTimeZone() {
  #if JS_HAS_INTL_API
 +  if (!timeZoneOverride_.empty()) {
 +    mozilla::Span<const char> tzid = mozilla::Span(timeZoneOverride_.data(), timeZoneOverride_.length());
-+    mozilla::intl::TimeZone::SetDefaultTimeZone(tzid);
++    auto result = mozilla::intl::TimeZone::SetDefaultTimeZone(tzid);
++    if (result.isErr()) {
++      fprintf(stderr, "ERROR: failed to setup default time zone\n");
++    }
 +    return;
 +  }
 +
@@ -2559,7 +2562,7 @@ diff --git a/widget/cocoa/NativeKeyBindings.mm b/widget/cocoa/NativeKeyBindings.
 index 2b11df66d9445080d4d8a19a915b3e00285c5d32..caef1b65bbcff899f45c3e3cddfe76e88479ec30 100644
 --- a/widget/cocoa/NativeKeyBindings.mm
 +++ b/widget/cocoa/NativeKeyBindings.mm
-@@ -491,6 +491,13 @@ void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+@@ -491,6 +491,13 @@
        break;
      case KEY_NAME_INDEX_ArrowLeft:
        if (aEvent.IsAlt()) {
@@ -2573,7 +2576,7 @@ index 2b11df66d9445080d4d8a19a915b3e00285c5d32..caef1b65bbcff899f45c3e3cddfe76e8
          break;
        }
        if (aEvent.IsMeta() || (aEvent.IsControl() && aEvent.IsShift())) {
-@@ -511,6 +518,13 @@ void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+@@ -511,6 +518,13 @@
        break;
      case KEY_NAME_INDEX_ArrowRight:
        if (aEvent.IsAlt()) {
@@ -2587,7 +2590,7 @@ index 2b11df66d9445080d4d8a19a915b3e00285c5d32..caef1b65bbcff899f45c3e3cddfe76e8
          break;
        }
        if (aEvent.IsMeta() || (aEvent.IsControl() && aEvent.IsShift())) {
-@@ -531,6 +545,10 @@ void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+@@ -531,6 +545,10 @@
        break;
      case KEY_NAME_INDEX_ArrowUp:
        if (aEvent.IsControl()) {
@@ -2598,7 +2601,7 @@ index 2b11df66d9445080d4d8a19a915b3e00285c5d32..caef1b65bbcff899f45c3e3cddfe76e8
          break;
        }
        if (aEvent.IsMeta()) {
-@@ -540,7 +558,7 @@ void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+@@ -540,7 +558,7 @@
          instance->AppendEditCommandsForSelector(
              !aEvent.IsShift()
                  ? ToObjcSelectorPtr(@selector(moveToBeginningOfDocument:))
@@ -2607,7 +2610,7 @@ index 2b11df66d9445080d4d8a19a915b3e00285c5d32..caef1b65bbcff899f45c3e3cddfe76e8
              aCommands);
          break;
        }
-@@ -563,6 +581,10 @@ void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+@@ -563,6 +581,10 @@
        break;
      case KEY_NAME_INDEX_ArrowDown:
        if (aEvent.IsControl()) {