diff --git a/Library/Homebrew/extend/ENV/shared.rb b/Library/Homebrew/extend/ENV/shared.rb
index c4585dff61..d81f3328bc 100644
--- a/Library/Homebrew/extend/ENV/shared.rb
+++ b/Library/Homebrew/extend/ENV/shared.rb
@@ -238,7 +238,6 @@ module SharedEnvExtension
 
   # Snow Leopard defines an NCURSES value the opposite of most distros.
   # @see https://bugs.python.org/issue6848
-  # Currently only used by aalib in core.
   sig { void }
   def ncurses_define
     odeprecated "ENV.ncurses_define"
diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index bfd4657b10..b94f31533f 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -97,7 +97,7 @@ module Stdenv
     old
   end
 
-  %w[O3 O2 O1 O0 Os].each do |opt|
+  %w[O3 O2 Os].each do |opt|
     define_method opt do
       odisabled "ENV.#{opt}"
 
@@ -106,6 +106,13 @@ module Stdenv
     end
   end
 
+  %w[O1 O0].each do |opt|
+    define_method opt do
+      send(:remove_from_cflags, /-O./)
+      send(:append_to_cflags, "-#{opt}")
+    end
+  end
+
   sig { returns(T.any(String, Pathname)) }
   def determine_cc
     s = super
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index 4d48592657..aae72826bb 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -344,7 +344,7 @@ module Superenv
     append_to_cccfg "O"
   end
 
-  %w[O3 O2 O1 O0 Os].each do |opt|
+  %w[O3 O2 Os].each do |opt|
     define_method opt do
       odisabled "ENV.#{opt}"
 
@@ -352,6 +352,12 @@ module Superenv
     end
   end
 
+  %w[O1 O0].each do |opt|
+    define_method opt do
+      send(:[]=, "HOMEBREW_OPTIMIZATION_LEVEL", opt)
+    end
+  end
+
   sig { void }
   def set_x11_env_if_installed
     odisabled "ENV.set_x11_env_if_installed"