diff --git a/Library/Homebrew/formula_cellar_checks.rb b/Library/Homebrew/formula_cellar_checks.rb
index f896caaf47..cd568a8466 100644
--- a/Library/Homebrew/formula_cellar_checks.rb
+++ b/Library/Homebrew/formula_cellar_checks.rb
@@ -7,6 +7,10 @@ require "utils/shell"
 #
 # @api private
 module FormulaCellarChecks
+  # If the location of HOMEBREW_LIBRARY changes
+  # keg_relocate.rb, test/global_spec.rb, and this constant need to change.
+  REPOSITORY_AND_NOT_LIBRARY_REGEX = %r{#{HOMEBREW_REPOSITORY}(?!/Library/)}.freeze
+
   def check_env_path(bin)
     # warn the user if stuff was installed outside of their PATH
     return unless bin.directory?
@@ -207,6 +211,26 @@ module FormulaCellarChecks
     EOS
   end
 
+  def check_repository_references(prefix)
+    return if HOMEBREW_PREFIX != HOMEBREW_REPOSITORY
+    return unless prefix.directory?
+
+    keg = Keg.new(prefix)
+
+    matches = []
+    keg.each_unique_file_matching(HOMEBREW_REPOSITORY) do |f|
+      matches << f.relative_path_from(keg.to_path) if f.read.match? REPOSITORY_AND_NOT_LIBRARY_REGEX
+    end
+
+    return if matches.empty?
+
+    <<~EOS
+      Files were found with references to the Homebrew repository directory
+      that are outside of the Library directory. The offending files are:
+        #{matches * "\n  "}
+    EOS
+  end
+
   def check_shim_references(prefix)
     return unless prefix.directory?
 
@@ -292,6 +316,7 @@ module FormulaCellarChecks
     problem_if_output(check_elisp_dirname(formula.share, formula.name))
     problem_if_output(check_elisp_root(formula.share, formula.name))
     problem_if_output(check_python_packages(formula.lib, formula.deps))
+    problem_if_output(check_repository_references(formula.prefix))
     problem_if_output(check_shim_references(formula.prefix))
     problem_if_output(check_plist(formula.prefix, formula.plist))
     problem_if_output(check_python_symlinks(formula.name, formula.keg_only?))
diff --git a/Library/Homebrew/keg_relocate.rb b/Library/Homebrew/keg_relocate.rb
index 0ea9544b33..a10ebe27b2 100644
--- a/Library/Homebrew/keg_relocate.rb
+++ b/Library/Homebrew/keg_relocate.rb
@@ -6,8 +6,12 @@ class Keg
   CELLAR_PLACEHOLDER = "@@HOMEBREW_CELLAR@@"
   REPOSITORY_PLACEHOLDER = "@@HOMEBREW_REPOSITORY@@"
 
-  Relocation = Struct.new(:old_prefix, :old_cellar, :old_repository,
-                          :new_prefix, :new_cellar, :new_repository) do
+  # If the location of HOMEBREW_LIBRARY changes
+  # formula_cellar_checks.rb, test/global_spec.rb, and this constant need to change.
+  LIBRARY_PLACEHOLDER = "@@HOMEBREW_REPOSITORY@@/Library"
+
+  Relocation = Struct.new(:old_prefix, :old_cellar, :old_repository, :old_library,
+                          :new_prefix, :new_cellar, :new_repository, :new_library) do
     # Use keyword args instead of positional args for initialization.
     def initialize(**kwargs)
       super(*members.map { |k| kwargs[k] })
@@ -40,9 +44,11 @@ class Keg
       old_prefix:     HOMEBREW_PREFIX.to_s,
       old_cellar:     HOMEBREW_CELLAR.to_s,
       old_repository: HOMEBREW_REPOSITORY.to_s,
+      old_library:    HOMEBREW_LIBRARY.to_s,
       new_prefix:     PREFIX_PLACEHOLDER,
       new_cellar:     CELLAR_PLACEHOLDER,
       new_repository: REPOSITORY_PLACEHOLDER,
+      new_library:    LIBRARY_PLACEHOLDER,
     )
     relocate_dynamic_linkage(relocation)
     replace_text_in_files(relocation)
@@ -53,9 +59,11 @@ class Keg
       old_prefix:     PREFIX_PLACEHOLDER,
       old_cellar:     CELLAR_PLACEHOLDER,
       old_repository: REPOSITORY_PLACEHOLDER,
+      old_library:    LIBRARY_PLACEHOLDER,
       new_prefix:     HOMEBREW_PREFIX.to_s,
       new_cellar:     HOMEBREW_CELLAR.to_s,
       new_repository: HOMEBREW_REPOSITORY.to_s,
+      new_library:    HOMEBREW_LIBRARY.to_s,
     )
     relocate_dynamic_linkage(relocation) unless skip_linkage
     replace_text_in_files(relocation, files: files)
@@ -74,7 +82,11 @@ class Keg
       }
       # when HOMEBREW_PREFIX == HOMEBREW_REPOSITORY we should use HOMEBREW_PREFIX for all relocations to avoid
       # being unable to differentiate between them.
-      replacements[relocation.old_repository] = relocation.new_repository if HOMEBREW_PREFIX != HOMEBREW_REPOSITORY
+      if HOMEBREW_PREFIX == HOMEBREW_REPOSITORY
+        replacements[relocation.old_library] = relocation.new_library
+      else
+        replacements[relocation.old_repository] = relocation.new_repository
+      end
       changed = s.gsub!(Regexp.union(replacements.keys.sort_by(&:length).reverse), replacements)
       next unless changed
 
diff --git a/Library/Homebrew/test/global_spec.rb b/Library/Homebrew/test/global_spec.rb
index 6c34ca8838..644c32bd16 100644
--- a/Library/Homebrew/test/global_spec.rb
+++ b/Library/Homebrew/test/global_spec.rb
@@ -8,4 +8,10 @@ describe "brew", :integration_test do
       .and not_to_output.to_stderr
       .and be_a_success
   end
+
+  # If the location of HOMEBREW_LIBRARY changes
+  # keg_relocate.rb, formula_cellar_checks.rb, and this test need to change.
+  it "ensures that HOMEBREW_LIBRARY=HOMEBREW_REPOSITORY/Library" do
+    expect(HOMEBREW_LIBRARY.to_s).to eq("#{HOMEBREW_REPOSITORY}/Library")
+  end
 end
diff --git a/bin/brew b/bin/brew
index d247d13264..d93497ef3e 100755
--- a/bin/brew
+++ b/bin/brew
@@ -58,6 +58,8 @@ then
   fi
 fi
 
+# If the location of HOMEBREW_LIBRARY changes
+# keg_relocate.rb, formula_cellar_checks.rb, and test/global_spec.rb need to change.
 HOMEBREW_LIBRARY="$HOMEBREW_REPOSITORY/Library"
 
 # Copy and export all HOMEBREW_* variables previously mentioned in