diff --git a/Library/Homebrew/.rubocop_todo.yml b/Library/Homebrew/.rubocop_todo.yml
index a2cb90aaec..5b30b296b4 100644
--- a/Library/Homebrew/.rubocop_todo.yml
+++ b/Library/Homebrew/.rubocop_todo.yml
@@ -12,6 +12,7 @@ Style/Documentation:
     - 'keg_relocate.rb'
     - 'os/linux/global.rb'
     - 'os/mac/architecture_list.rb'
+    - 'os/mac/global.rb'
     - 'os/mac/keg.rb'
     - 'reinstall.rb'
     - 'software_spec.rb'
diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index 756ca25c85..9bcccedbca 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -164,7 +164,7 @@ rescue BuildError => e
   if e.formula.head? || e.formula.deprecated? || e.formula.disabled?
     $stderr.puts <<~EOS
       Please create pull requests instead of asking for help on Homebrew's GitHub,
-      Discourse, Twitter or IRC.
+      Discourse, Twitter or any other official channels.
     EOS
   end
 
diff --git a/Library/Homebrew/dev-cmd/bottle.rb b/Library/Homebrew/dev-cmd/bottle.rb
index 45fba5500e..4f6d117609 100644
--- a/Library/Homebrew/dev-cmd/bottle.rb
+++ b/Library/Homebrew/dev-cmd/bottle.rb
@@ -15,7 +15,9 @@ BOTTLE_ERB = <<-EOS
     <% if root_url != "#{HOMEBREW_BOTTLE_DEFAULT_DOMAIN}/bottles" %>
     root_url "<%= root_url %>"
     <% end %>
-    <% if ![HOMEBREW_DEFAULT_PREFIX, LINUXBREW_DEFAULT_PREFIX].include?(prefix) %>
+    <% if ![HOMEBREW_DEFAULT_PREFIX,
+            HOMEBREW_MACOS_ARM_DEFAULT_PREFIX,
+            HOMEBREW_LINUX_DEFAULT_PREFIX].include?(prefix) %>
     prefix "<%= prefix %>"
     <% end %>
     <% if cellar.is_a? Symbol %>
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 85d8a73ce7..0964ca0be1 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -112,8 +112,9 @@ module Homebrew
         <<~EOS
           You will encounter build failures with some formulae.
           Please create pull requests instead of asking for help on Homebrew's GitHub,
-          Discourse, Twitter or IRC. You are responsible for resolving any issues you
-          experience while you are running this #{what}.
+          Discourse, Twitter or any other official channels. You are responsible for
+          resolving any issues you experience while you are running this
+          #{what}.
         EOS
       end
 
diff --git a/Library/Homebrew/extend/os/mac/diagnostic.rb b/Library/Homebrew/extend/os/mac/diagnostic.rb
index 46974b7f61..1e636f15ff 100644
--- a/Library/Homebrew/extend/os/mac/diagnostic.rb
+++ b/Library/Homebrew/extend/os/mac/diagnostic.rb
@@ -63,6 +63,7 @@ module Homebrew
 
       def supported_configuration_checks
         %w[
+          check_for_unsupported_arch
           check_for_unsupported_macos
         ].freeze
       end
@@ -90,21 +91,35 @@ module Homebrew
         nil
       end
 
+      def check_for_unsupported_arch
+        return if Homebrew::EnvConfig.developer?
+        return unless Hardware::CPU.arm?
+
+        <<~EOS
+          You are running macOS on a #{Hardware::CPU.arch} CPU architecture.
+          We do not provide support for this (yet).
+          Reinstall Homebrew under Rosetta 2 until we support it.
+          #{please_create_pull_requests}
+        EOS
+      end
+
       def check_for_unsupported_macos
         return if Homebrew::EnvConfig.developer?
 
-        # TODO: remove when Big Sur is released.
-        return if MacOS.version == :big_sur && ENV["HOMEBREW_GITHUB_ACTIONS_BIG_SUR_TESTING"]
-
         who = +"We"
-        if OS::Mac.prerelease?
-          what = "pre-release version"
+        # TODO: remove when Big Sur is supported.
+        what = if MacOS.version == :big_sur
+          return if ENV["HOMEBREW_GITHUB_ACTIONS_BIG_SUR_TESTING"]
+
+          "released but not yet supported version"
+        elsif OS::Mac.prerelease?
+          "pre-release version"
         elsif OS::Mac.outdated_release?
           who << " (and Apple)"
-          what = "old version"
-        else
-          return
+          "old version"
         end
+        return if what.blank?
+
         who.freeze
 
         <<~EOS
diff --git a/Library/Homebrew/extend/os/mac/hardware/cpu.rb b/Library/Homebrew/extend/os/mac/hardware/cpu.rb
index 2d33360382..746786f98d 100644
--- a/Library/Homebrew/extend/os/mac/hardware/cpu.rb
+++ b/Library/Homebrew/extend/os/mac/hardware/cpu.rb
@@ -64,11 +64,11 @@ module Hardware
         [arch_64_bit, arch_32_bit].extend ArchitectureListExtension
       end
 
-      # True when running under an Intel-based shell via Rosetta on an
+      # True when running under an Intel-based shell via Rosetta 2 on an
       # Apple Silicon Mac. This can be detected via seeing if there's a
       # conflict between what `uname` reports and the underlying `sysctl` flags,
-      # since the `sysctl` flags don't change behaviour under Rosetta.
-      def in_rosetta?
+      # since the `sysctl` flags don't change behaviour under Rosetta 2.
+      def in_rosetta2?
         intel? && physical_cpu_arm64?
       end
 
@@ -116,14 +116,14 @@ module Hardware
         sysctl_bool("hw.optional.sse4_2")
       end
 
-      private
-
       # Note: this is more reliable than checking uname.
-      # `sysctl` returns the right answer even when running in Rosetta.
+      # `sysctl` returns the right answer even when running in Rosetta 2.
       def physical_cpu_arm64?
         sysctl_bool("hw.optional.arm64")
       end
 
+      private
+
       def sysctl_bool(key)
         sysctl_int(key) == 1
       end
diff --git a/Library/Homebrew/extend/os/mac/system_config.rb b/Library/Homebrew/extend/os/mac/system_config.rb
index 1f17e08c7f..7faa0f7261 100644
--- a/Library/Homebrew/extend/os/mac/system_config.rb
+++ b/Library/Homebrew/extend/os/mac/system_config.rb
@@ -51,6 +51,7 @@ module SystemConfig
       f.puts "CLT: #{clt || "N/A"}"
       f.puts "Xcode: #{xcode || "N/A"}"
       f.puts "XQuartz: #{xquartz}" if xquartz
+      f.puts "Rosetta 2: #{Hardware::CPU.in_rosetta2?}" if Hardware::CPU.physical_cpu_arm64?
     end
   end
 end
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index ce2d502060..aae10e1af1 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -235,12 +235,17 @@ class FormulaInstaller
     recursive_formulae = recursive_deps.map(&:to_formula)
 
     recursive_dependencies = []
+    invalid_arch_dependencies = []
     recursive_formulae.each do |dep|
       dep_recursive_dependencies = dep.recursive_dependencies.map(&:to_s)
       if dep_recursive_dependencies.include?(formula.name)
         recursive_dependencies << "#{formula.full_name} depends on #{dep.full_name}"
         recursive_dependencies << "#{dep.full_name} depends on #{formula.full_name}"
       end
+
+      if (tab = Tab.for_formula(dep)) && tab.arch.present? && tab.arch.to_s != Hardware::CPU.arch.to_s
+        invalid_arch_dependencies << "#{dep} was built for #{tab.arch}"
+      end
     end
 
     unless recursive_dependencies.empty?
@@ -258,6 +263,13 @@ class FormulaInstaller
       EOS
     end
 
+    unless invalid_arch_dependencies.empty?
+      raise CannotInstallFormulaError, <<~EOS
+        #{formula.full_name} dependencies not built for the #{Hardware::CPU.arch} CPU architecture:
+          #{invalid_arch_dependencies.join("\n  ")}
+      EOS
+    end
+
     pinned_unsatisfied_deps = recursive_deps.select do |dep|
       dep.to_formula.pinned? && !dep.satisfied?(inherited_options_for(dep))
     end
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index af73b4e4df..2cc272a7f5 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -69,7 +69,8 @@ HOMEBREW_USER_AGENT_FAKE_SAFARI =
   "(KHTML, like Gecko) Version/10.0.3 Safari/602.4.8"
 
 HOMEBREW_DEFAULT_PREFIX = "/usr/local"
-LINUXBREW_DEFAULT_PREFIX = "/home/linuxbrew/.linuxbrew"
+HOMEBREW_MACOS_ARM_DEFAULT_PREFIX = "/opt/homebrew"
+HOMEBREW_LINUX_DEFAULT_PREFIX = "/home/linuxbrew/.linuxbrew"
 
 require "fileutils"
 require "os/global"
diff --git a/Library/Homebrew/hardware.rb b/Library/Homebrew/hardware.rb
index 05b5d08ad9..11c78eaf58 100644
--- a/Library/Homebrew/hardware.rb
+++ b/Library/Homebrew/hardware.rb
@@ -156,7 +156,7 @@ module Hardware
         "-march=#{arch}"
       end
 
-      def in_rosetta?
+      def in_rosetta2?
         false
       end
     end
diff --git a/Library/Homebrew/install.rb b/Library/Homebrew/install.rb
index f00d3fc402..155a480996 100644
--- a/Library/Homebrew/install.rb
+++ b/Library/Homebrew/install.rb
@@ -14,6 +14,7 @@ module Homebrew
     module_function
 
     def perform_preinstall_checks(all_fatal: false, cc: nil)
+      check_prefix
       check_cpu
       attempt_directory_creation
       check_cc_argv(cc)
@@ -28,20 +29,34 @@ module Homebrew
       Diagnostic.checks(:build_from_source_checks, fatal: all_fatal)
     end
 
+    def check_prefix
+      if Hardware::CPU.intel? && HOMEBREW_PREFIX.to_s == HOMEBREW_MACOS_ARM_DEFAULT_PREFIX
+        odie "Cannot install in Homebrew on Intel processor in ARM default prefix (#{HOMEBREW_PREFIX})!"
+      elsif Hardware::CPU.arm? && HOMEBREW_PREFIX.to_s == HOMEBREW_DEFAULT_PREFIX
+        odie <<~EOS
+          Cannot install in Homebrew on ARM processor in Intel default prefix (#{HOMEBREW_PREFIX})!
+          Please create a new installation in #{HOMEBREW_MACOS_ARM_DEFAULT_PREFIX} using one of the
+          "Alternative Installs" from:
+            #{Formatter.url("https://docs.brew.sh/Installation")}
+          You can migrate your previously installed formula list with:
+            brew bundle dump
+        EOS
+      end
+    end
+
     def check_cpu
       return if Hardware::CPU.intel? && Hardware::CPU.is_64_bit?
 
-      message = "Sorry, Homebrew does not support your computer's CPU architecture!"
-      if Hardware::CPU.arm?
-        opoo message
-        return
-      elsif Hardware::CPU.ppc?
-        message += <<~EOS
-          For PowerPC Mac (PPC32/PPC64BE) support, see:
-            #{Formatter.url("https://github.com/mistydemeo/tigerbrew")}
-        EOS
-      end
-      abort message
+      # Handled by check_for_unsupported_arch in extend/os/mac/diagnostic.rb
+      return if Hardware::CPU.arm?
+
+      return unless Hardware::CPU.ppc?
+
+      odie <<~EOS
+        Sorry, Homebrew does not support your computer's CPU architecture!
+        For PowerPC Mac (PPC32/PPC64BE) support, see:
+          #{Formatter.url("https://github.com/mistydemeo/tigerbrew")}
+      EOS
     end
     private_class_method :check_cpu
 
diff --git a/Library/Homebrew/os/global.rb b/Library/Homebrew/os/global.rb
index bbf58536d7..f96f565a4e 100644
--- a/Library/Homebrew/os/global.rb
+++ b/Library/Homebrew/os/global.rb
@@ -1,4 +1,8 @@
 # typed: strict
 # frozen_string_literal: true
 
-require "os/linux/global" if OS.linux?
+if OS.mac?
+  require "os/mac/global"
+elsif OS.linux?
+  require "os/linux/global"
+end
diff --git a/Library/Homebrew/os/linux/global.rb b/Library/Homebrew/os/linux/global.rb
index 370fa38ed2..891d5a24c7 100644
--- a/Library/Homebrew/os/linux/global.rb
+++ b/Library/Homebrew/os/linux/global.rb
@@ -12,6 +12,6 @@ module Homebrew
   DEFAULT_PREFIX ||= if Homebrew::EnvConfig.force_homebrew_on_linux?
     HOMEBREW_DEFAULT_PREFIX
   else
-    LINUXBREW_DEFAULT_PREFIX
+    HOMEBREW_LINUX_DEFAULT_PREFIX
   end.freeze
 end
diff --git a/Library/Homebrew/os/mac/global.rb b/Library/Homebrew/os/mac/global.rb
new file mode 100644
index 0000000000..90cc213d62
--- /dev/null
+++ b/Library/Homebrew/os/mac/global.rb
@@ -0,0 +1,10 @@
+# typed: false
+# frozen_string_literal: true
+
+module Homebrew
+  DEFAULT_PREFIX ||= if Hardware::CPU.arm?
+    HOMEBREW_MACOS_ARM_DEFAULT_PREFIX
+  else
+    HOMEBREW_DEFAULT_PREFIX
+  end.freeze
+end
diff --git a/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi b/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
index 00bacb7826..24874c0019 100644
--- a/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
+++ b/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
@@ -13404,8 +13404,10 @@ class Object
   HOMEBREW_LIBRARY = ::T.let(nil, ::T.untyped)
   HOMEBREW_LIBRARY_PATH = ::T.let(nil, ::T.untyped)
   HOMEBREW_LINKED_KEGS = ::T.let(nil, ::T.untyped)
+  HOMEBREW_LINUX_DEFAULT_PREFIX = ::T.let(nil, ::T.untyped)
   HOMEBREW_LOCKS = ::T.let(nil, ::T.untyped)
   HOMEBREW_LOGS = ::T.let(nil, ::T.untyped)
+  HOMEBREW_MACOS_ARM_DEFAULT_PREFIX = ::T.let(nil, ::T.untyped)
   HOMEBREW_OFFICIAL_REPO_PREFIXES_REGEX = ::T.let(nil, ::T.untyped)
   HOMEBREW_PATCHELF_RB_WRITE = ::T.let(nil, ::T.untyped)
   HOMEBREW_PINNED_KEGS = ::T.let(nil, ::T.untyped)
@@ -13428,7 +13430,6 @@ class Object
   HOMEBREW_VERSION = ::T.let(nil, ::T.untyped)
   HOMEBREW_WWW = ::T.let(nil, ::T.untyped)
   HOMEPAGE_URL = ::T.let(nil, ::T.untyped)
-  LINUXBREW_DEFAULT_PREFIX = ::T.let(nil, ::T.untyped)
   MAXIMUM_STRING_MATCHES = ::T.let(nil, ::T.untyped)
   OFFICIAL_CASK_TAPS = ::T.let(nil, ::T.untyped)
   OFFICIAL_CMD_TAPS = ::T.let(nil, ::T.untyped)
diff --git a/Library/Homebrew/tab.rb b/Library/Homebrew/tab.rb
index 5cc7e5e789..4d6a4a7728 100644
--- a/Library/Homebrew/tab.rb
+++ b/Library/Homebrew/tab.rb
@@ -186,6 +186,7 @@ class Tab < OpenStruct
       "compiler"                => DevelopmentTools.default_compiler,
       "aliases"                 => [],
       "runtime_dependencies"    => nil,
+      "arch"                    => nil,
       "source"                  => {
         "path"     => nil,
         "tap"      => nil,
@@ -345,6 +346,7 @@ class Tab < OpenStruct
       "aliases"                 => aliases,
       "runtime_dependencies"    => runtime_dependencies,
       "source"                  => source,
+      "arch"                    => Hardware::CPU.arch,
       "built_on"                => built_on,
     }
 
diff --git a/docs/Installation.md b/docs/Installation.md
index 461a603a34..af2951bac6 100644
--- a/docs/Installation.md
+++ b/docs/Installation.md
@@ -31,10 +31,11 @@ Just extract (or `git clone`) Homebrew wherever you want. Just avoid:
 * `/tmp` subdirectories because Homebrew gets upset.
 * `/sw` and `/opt/local` because build scripts get confused when Homebrew is there instead of Fink or MacPorts, respectively.
 
-However do yourself a favour and install to `/usr/local`. Some things may
+However do yourself a favour and install to `/usr/local` on macOS Intel, `/opt/homebrew` on macOS ARM
+and `.home/linuxbrew/.linuxbrew` on Linux. Some things may
 not build when installed elsewhere. One of the reasons Homebrew just
 works relative to the competition is **because** we recommend installing
-to `/usr/local`. *Pick another prefix at your peril!*
+here. *Pick another prefix at your peril!*
 
 ```sh
 mkdir homebrew && curl -L https://github.com/Homebrew/brew/tarball/master | tar xz --strip 1 -C homebrew