diff --git a/lib/spack/spack/binary_distribution.py b/lib/spack/spack/binary_distribution.py
index 81ac908b36..a406101d2c 100644
--- a/lib/spack/spack/binary_distribution.py
+++ b/lib/spack/spack/binary_distribution.py
@@ -1796,7 +1796,15 @@ def is_backup_file(file):
         relocate.relocate_text(text_names, prefix_to_prefix_text)
 
         # relocate the install prefixes in binary files including dependencies
-        relocate.relocate_text_bin(files_to_relocate, prefix_to_prefix_bin)
+        changed_files = relocate.relocate_text_bin(files_to_relocate, prefix_to_prefix_bin)
+
+        # Add ad-hoc signatures to patched macho files when on macOS.
+        if "macho" in platform.binary_formats and sys.platform == "darwin":
+            codesign = which("codesign")
+            if not codesign:
+                return
+            for binary in changed_files:
+                codesign("-fs-", binary)
 
     # If we are installing back to the same location
     # relocate the sbang location if the spack directory changed
diff --git a/lib/spack/spack/relocate.py b/lib/spack/spack/relocate.py
index 2303bf22a2..52811dd8cc 100644
--- a/lib/spack/spack/relocate.py
+++ b/lib/spack/spack/relocate.py
@@ -675,7 +675,7 @@ def relocate_text_bin(binaries, prefixes):
     Raises:
       spack.relocate_text.BinaryTextReplaceError: when the new path is longer than the old path
     """
-    BinaryFilePrefixReplacer.from_strings_or_bytes(prefixes).apply(binaries)
+    return BinaryFilePrefixReplacer.from_strings_or_bytes(prefixes).apply(binaries)
 
 
 def is_relocatable(spec):
diff --git a/lib/spack/spack/relocate_text.py b/lib/spack/spack/relocate_text.py
index 5d91f75474..bfabcc8632 100644
--- a/lib/spack/spack/relocate_text.py
+++ b/lib/spack/spack/relocate_text.py
@@ -73,24 +73,28 @@ def is_noop(self) -> bool:
         """Returns true when the prefix to prefix map
         is mapping everything to the same location (identity)
         or there are no prefixes to replace."""
-        return not bool(self.prefix_to_prefix)
+        return not self.prefix_to_prefix
 
     def apply(self, filenames: list):
+        """Returns a list of files that were modified"""
+        changed_files = []
         if self.is_noop:
-            return
+            return []
         for filename in filenames:
-            self.apply_to_filename(filename)
+            if self.apply_to_filename(filename):
+                changed_files.append(filename)
+        return changed_files
 
     def apply_to_filename(self, filename):
         if self.is_noop:
-            return
+            return False
         with open(filename, "rb+") as f:
-            self.apply_to_file(f)
+            return self.apply_to_file(f)
 
     def apply_to_file(self, f):
         if self.is_noop:
-            return
-        self._apply_to_file(f)
+            return False
+        return self._apply_to_file(f)
 
 
 class TextFilePrefixReplacer(PrefixReplacer):
@@ -122,10 +126,11 @@ def _apply_to_file(self, f):
         data = f.read()
         new_data = re.sub(self.regex, replacement, data)
         if id(data) == id(new_data):
-            return
+            return False
         f.seek(0)
         f.write(new_data)
         f.truncate()
+        return True
 
 
 class BinaryFilePrefixReplacer(PrefixReplacer):
@@ -194,6 +199,9 @@ def _apply_to_file(self, f):
 
         Arguments:
             f: file opened in rb+ mode
+
+        Returns:
+            bool: True if file was modified
         """
         assert f.tell() == 0
 
@@ -201,6 +209,8 @@ def _apply_to_file(self, f):
         # but it's nasty to deal with matches across boundaries, so let's stick to
         # something simple.
 
+        modified = True
+
         for match in self.regex.finditer(f.read()):
             # The matching prefix (old) and its replacement (new)
             old = match.group(1)
@@ -243,6 +253,9 @@ def _apply_to_file(self, f):
 
             f.seek(match.start())
             f.write(replacement)
+            modified = True
+
+        return modified
 
 
 class BinaryStringReplacementError(spack.error.SpackError):