diff --git a/CHANGES.txt b/CHANGES.txt
index 4ef9bdbac5..a1cc0bfb2c 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -25,9 +25,14 @@ Unreleased Changes (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
   * 6x speedup in ArrayEncoder.writeUInt32NotTag
 
   Python
-  * Added UnknownFieldSet(message) for pure Python. The old
-    message.UnknownFields() will be deprecated after UnknownFieldSet(message) is
-    added for cpp extension.
+  * The C extension module for Python has been rewritten to use the upb library.
+    This is expected to deliver significant performance benefits, especially when
+    parsing large payloads.  There are some minor breaking changes, but these
+    should not impact most users.  For more information see:
+    https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates
+  * Due to the breaking changes for Python, the major version number for Python
+    has been incremented.
+  * The binary wheel for macOS now supports Apple silicon.
 
 2022-04-21 version 3.20.1 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
 
diff --git a/protobuf_deps.bzl b/protobuf_deps.bzl
index eab12e33cb..0f3c76aacc 100644
--- a/protobuf_deps.bzl
+++ b/protobuf_deps.bzl
@@ -114,6 +114,6 @@ def protobuf_deps():
         _github_archive(
             name = "upb",
             repo = "https://github.com/protocolbuffers/upb",
-            commit = "0e8772fc20e5a0a2fa1f326c79d494374871ef94",
-            sha256 = "2a7ccd5a8e20c5b2f6efafb305f734c7ad1cc5615706f7a35cd4fbad436d5101",
+            commit = "c3cfd09b0184bcbdade71a3d788df02c83e897f2",
+            sha256 = "4a9f79385fc0c1e3e7ba5c34220db53f956c8c42d636bafc6a563da2facf8c3f",
         )
diff --git a/protobuf_version.bzl b/protobuf_version.bzl
index 13955260a7..19c77cfdc6 100644
--- a/protobuf_version.bzl
+++ b/protobuf_version.bzl
@@ -1,6 +1,3 @@
 PROTOC_VERSION = '3.20.1'
 PROTOBUF_JAVA_VERSION = '3.20.1'
 PROTOBUF_PYTHON_VERSION = '3.20.1'
-
-# Remove once upb has been updated to use PROTOBUF_PYTHON_VERSION instead.
-PROTOBUF_VERSION = PROTOBUF_PYTHON_VERSION
diff --git a/toolchain/cc_toolchain_config.bzl b/toolchain/cc_toolchain_config.bzl
index 777bb82f9a..2599477778 100644
--- a/toolchain/cc_toolchain_config.bzl
+++ b/toolchain/cc_toolchain_config.bzl
@@ -6,6 +6,7 @@ load(
     "flag_group",
     "flag_set",
     "tool_path",
+    "with_feature_set",
 )
 
 all_link_actions = [
@@ -154,10 +155,31 @@ def _impl(ctx):
                   ),
               ],
           ),
+          flag_set(
+              actions = all_compile_actions,
+              flag_groups = [flag_group(flags = ["-DNDEBUG", "-O3"])],
+              with_features = [with_feature_set(features = ["opt"])],
+          ),
+          flag_set(
+              actions = all_compile_actions,
+              flag_groups = [flag_group(flags = ["-g"])],
+              with_features = [with_feature_set(features = ["dbg"])],
+          ),
+          flag_set(
+              actions = all_compile_actions,
+              flag_groups = [flag_group(flags = ["-O1"])],
+              with_features = [with_feature_set(features = ["fastbuild"])],
+          ),
       ],
   )
 
-  features = [linker_flags, compiler_flags, sysroot_flags]
+  features = [
+      linker_flags,
+      compiler_flags,
+      sysroot_flags,
+      feature(name = "dbg"),
+      feature(name = "opt"),
+  ]
 
   if "mingw" in ctx.attr.target_full_name:
       features.append(