diff --git a/Formula/python@3.9.rb b/Formula/python@3.9.rb
index db6a514b5b211..6f46f0d9316c2 100644
--- a/Formula/python@3.9.rb
+++ b/Formula/python@3.9.rb
@@ -1,8 +1,8 @@
 class PythonAT39 < Formula
   desc "Interpreted, interactive, object-oriented programming language"
   homepage "https://www.python.org/"
-  url "https://www.python.org/ftp/python/3.9.0/Python-3.9.0.tar.xz"
-  sha256 "9c73e63c99855709b9be0b3cc9e5b072cb60f37311e8c4e50f15576a0bf82854"
+  url "https://www.python.org/ftp/python/3.9.1/Python-3.9.1rc1.tar.xz"
+  sha256 "ca0fa2ddc5cf07770d128cfe2dda44b8e47885e4bab6012ce40a7de1be084138"
   license "Python-2.0"
   revision 2
 
@@ -12,9 +12,10 @@ class PythonAT39 < Formula
   end
 
   bottle do
-    sha256 "9ad938e5803a6c8ce6fb183f479968cadc1d6b6cb75dd7a11d4761c5e3635131" => :big_sur
-    sha256 "a39639719e49bf3631ef41705267eae5ae06b78aebc0e8c3ffd9fdb91e75d56c" => :catalina
-    sha256 "4462c76fea0dc7abb9ea959d82594aa0b10191f5bc3e43d8d44131a05bee3950" => :mojave
+    sha256 "bd4ebe03f4c8371c87b2e2db46d5a8ebe0d3f2940f64d8228b901048f1dd9290" => :big_sur
+    sha256 "fb4e0fa1e5bd0801809e88ee99df2640974bb3953e0ebfe56541ff1ba2fd4865" => :catalina
+    sha256 "77254b7bca66680c41db33e78d40bef288924fb142deb73648ce67255c6dda83" => :mojave
+    sha256 "2e1dec264883dd4ee263a89ff41c5bb6579bbf68982ca40652bb8131d1f51e66" => :high_sierra
   end
 
   # setuptools remembers the build flags python is built with and uses them to
@@ -75,16 +76,6 @@ class PythonAT39 < Formula
     sha256 "99a22d87add3f634ff917310a3d87e499f19e663413a52eb9232c447aa646c9f"
   end
 
-  # Remove this block when upstream adds arm64 and Big Sur compatibility
-  if MacOS.version >= :big_sur
-    # Upstream PRs #20171, #21114, #21224 and #21249
-    # Backport of https://github.com/python/cpython/pull/22855
-    patch do
-      url "https://raw.githubusercontent.com/Homebrew/formula-patches/33a9d63f/python/arm64-3.9.patch"
-      sha256 "167e328cf68e9ec142f483fda9fafbb903be9a47dee2826614fdc24b2fbe6e06"
-    end
-  end
-
   def install
     # Unset these so that installing pip and setuptools puts them where we want
     # and not into some other Python the user has installed.
@@ -121,7 +112,16 @@ def install
       cflags << "-I#{MacOS.sdk_path}/System/Library/Frameworks/Tk.framework/Versions/8.5/Headers"
     end
     # Avoid linking to libgcc https://mail.python.org/pipermail/python-dev/2012-February/116205.html
-    args << "MACOSX_DEPLOYMENT_TARGET=#{MacOS.version}"
+
+    # Big Sur normally returns a value of 11.0 for the macOS version, but Python expects
+    # 10.x version numbers
+    if MacOS.version >= :big_sur
+      ENV["SYSTEM_VERSION_COMPAT"] = "1"
+      macosversion = system "sw_vers", "-productVersion"
+      args << "MACOSX_DEPLOYMENT_TARGET=#{macosversion}"
+    else
+      args << "MACOSX_DEPLOYMENT_TARGET=#{MacOS.version}"
+    end
 
     # We want our readline! This is just to outsmart the detection code,
     # superenv makes cc always find includes/libs!
@@ -305,9 +305,9 @@ def sitecustomize
           # site_packages; prefer the shorter paths
           long_prefix = re.compile(r'#{rack}/[0-9\._abrc]+/Frameworks/Python\.framework/Versions/#{xy}/lib/python#{xy}/site-packages')
           sys.path = [long_prefix.sub('#{HOMEBREW_PREFIX/"lib/python#{xy}/site-packages"}', p) for p in sys.path]
-          # Set the sys.executable to use the opt_prefix. Only do this if PYTHONEXECUTABLE is not
-          # explicitly set and we are not in a virtualenv:
-          if 'PYTHONEXECUTABLE' not in os.environ and sys.prefix == sys.base_prefix:
+          # Set the sys.executable to use the opt_prefix, unless explicitly set
+          # with PYTHONEXECUTABLE:
+          if 'PYTHONEXECUTABLE' not in os.environ:
               sys.executable = '#{opt_bin}/python#{xy}'
     EOS
   end
@@ -321,20 +321,16 @@ def caveats
     <<~EOS
       Python has been installed as
         #{HOMEBREW_PREFIX}/bin/python3
-
       Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
       `python3`, `python3-config`, `pip3` etc., respectively, have been installed into
         #{opt_libexec}/bin
-
       You can install Python packages with
         pip3 install <package>
       They will install into the site-package directory
         #{HOMEBREW_PREFIX/"lib/python#{xy}/site-packages"}
-
       See: https://docs.brew.sh/Homebrew-and-Python
     EOS
   end
-
   test do
     xy = (prefix/"Frameworks/Python.framework/Versions").children.min.basename.to_s
     # Check if sqlite is ok, because we build with --enable-loadable-sqlite-extensions