diff --git a/tools/versioner/src/Utils.cpp b/tools/versioner/src/Utils.cpp
index ef7facc..ca186a4 100644
--- a/tools/versioner/src/Utils.cpp
+++ b/tools/versioner/src/Utils.cpp
@@ -37,7 +37,8 @@
   return buf;
 }
 
-std::vector<std::string> collectHeaders(const std::string& directory) {
+std::vector<std::string> collectHeaders(const std::string& directory,
+                                        const std::unordered_set<std::string>& ignored_directories) {
   std::vector<std::string> headers;
 
   char* dir_argv[2] = { const_cast<char*>(directory.c_str()), nullptr };
@@ -48,16 +49,34 @@
     err(1, "failed to open directory '%s'", directory.c_str());
   }
 
+  FTSENT* skipping = nullptr;
   while (FTSENT* ent = fts_read(fts.get())) {
-    if (ent->fts_info & (FTS_D | FTS_DP)) {
+    if (ent->fts_info & FTS_DP) {
+      if (ent == skipping) {
+        skipping = nullptr;
+      }
       continue;
     }
 
-    if (!android::base::EndsWith(ent->fts_path, ".h")) {
+    if (skipping != nullptr) {
       continue;
     }
 
-    headers.push_back(ent->fts_path);
+    if (ent->fts_info & FTS_D) {
+      if (ignored_directories.count(ent->fts_path) != 0) {
+        // fts_read guarantees that `ent` is valid and sane to hold on to until
+        // after it's returned with FTS_DP set.
+        skipping = ent;
+      }
+      continue;
+    }
+
+    std::string path = ent->fts_path;
+    if (!android::base::EndsWith(path, ".h")) {
+      continue;
+    }
+
+    headers.push_back(std::move(path));
   }
 
   return headers;
diff --git a/tools/versioner/src/Utils.h b/tools/versioner/src/Utils.h
index 44a34f8..9b45dcd 100644
--- a/tools/versioner/src/Utils.h
+++ b/tools/versioner/src/Utils.h
@@ -22,12 +22,14 @@
 #include <unistd.h>
 
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 #include <llvm/ADT/StringRef.h>
 
 std::string getWorkingDir();
-std::vector<std::string> collectHeaders(const std::string& directory);
+std::vector<std::string> collectHeaders(const std::string& directory,
+                                        const std::unordered_set<std::string>& ignored_directories);
 
 static inline std::string dirname(const std::string& path) {
   std::unique_ptr<char, decltype(&free)> path_copy(strdup(path.c_str()), free);
diff --git a/tools/versioner/src/versioner.cpp b/tools/versioner/src/versioner.cpp
index 735ea04..bb09bea 100644
--- a/tools/versioner/src/versioner.cpp
+++ b/tools/versioner/src/versioner.cpp
@@ -44,6 +44,7 @@
 #include <android-base/file.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
+#include <android-base/strings.h>
 
 #include "Arch.h"
 #include "DeclarationDatabase.h"
@@ -78,11 +79,21 @@
 #endif
 }
 
-static CompilationRequirements collectRequirements(const Arch& arch, const std::string& header_dir,
-                                                   const std::string& dependency_dir) {
-  std::vector<std::string> headers = collectHeaders(header_dir);
-  std::vector<std::string> dependencies = { header_dir };
-  if (!dependency_dir.empty()) {
+namespace {
+struct HeaderLocationInformation {
+  std::string header_dir;
+  std::string dependency_dir;
+  // Absolute paths to ignore all children -- including subdirectories -- of.
+  std::unordered_set<std::string> ignored_directories;
+};
+}
+
+static CompilationRequirements collectRequirements(const Arch& arch,
+                                                   const HeaderLocationInformation& location) {
+  std::vector<std::string> headers =
+      collectHeaders(location.header_dir, location.ignored_directories);
+  std::vector<std::string> dependencies = { location.header_dir };
+  if (!location.dependency_dir.empty()) {
     auto collect_children = [&dependencies](const std::string& dir_path) {
       DIR* dir = opendir(dir_path.c_str());
       if (!dir) {
@@ -113,8 +124,8 @@
       closedir(dir);
     };
 
-    collect_children(dependency_dir + "/common");
-    collect_children(dependency_dir + "/" + to_string(arch));
+    collect_children(location.dependency_dir + "/common");
+    collect_children(location.dependency_dir + "/" + to_string(arch));
   }
 
   auto new_end = std::remove_if(headers.begin(), headers.end(), [&arch](llvm::StringRef header) {
@@ -158,13 +169,12 @@
 }
 
 static std::unique_ptr<HeaderDatabase> compileHeaders(const std::set<CompilationType>& types,
-                                                      const std::string& header_dir,
-                                                      const std::string& dependency_dir) {
+                                                      const HeaderLocationInformation& location) {
   if (types.empty()) {
     errx(1, "compileHeaders received no CompilationTypes");
   }
 
-  auto vfs = createCommonVFS(header_dir, dependency_dir, add_include);
+  auto vfs = createCommonVFS(location.header_dir, location.dependency_dir, add_include);
 
   size_t thread_count = max_thread_count;
   std::vector<std::thread> threads;
@@ -175,7 +185,7 @@
   auto result = std::make_unique<HeaderDatabase>();
   for (const auto& type : types) {
     if (requirements.count(type.arch) == 0) {
-      requirements[type.arch] = collectRequirements(type.arch, header_dir, dependency_dir);
+      requirements[type.arch] = collectRequirements(type.arch, location);
     }
   }
 
@@ -438,6 +448,7 @@
     fprintf(stderr, "  -f\t\tpreprocess header files even if validation fails\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "Miscellaneous:\n");
+    fprintf(stderr, "  -F\t\tdo not ignore FORTIFY headers by default\n");
     fprintf(stderr, "  -d\t\tdump function availability\n");
     fprintf(stderr, "  -j THREADS\tmaximum number of threads to use\n");
     fprintf(stderr, "  -v\t\tenable verbose logging\n");
@@ -461,9 +472,10 @@
   std::string preprocessor_output_path;
   bool force = false;
   bool dump = false;
+  bool ignore_fortify_headers = true;
 
   int c;
-  while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhi")) != -1) {
+  while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhFi")) != -1) {
     default_args = false;
     switch (c) {
       case 'a': {
@@ -549,6 +561,10 @@
         add_include = true;
         break;
 
+      case 'F':
+        ignore_fortify_headers = false;
+        break;
+
       default:
         usage();
         break;
@@ -559,8 +575,7 @@
     usage();
   }
 
-  std::string header_dir;
-  std::string dependency_dir;
+  HeaderLocationInformation location;
 
   const char* top = getenv("ANDROID_BUILD_TOP");
   if (!top && (optind == argc || add_include)) {
@@ -571,21 +586,32 @@
   if (optind == argc) {
     // Neither HEADER_PATH nor DEPS_PATH were specified, so try to figure them out.
     std::string versioner_dir = to_string(top) + "/bionic/tools/versioner";
-    header_dir = versioner_dir + "/current";
-    dependency_dir = versioner_dir + "/dependencies";
+    location.header_dir = versioner_dir + "/current";
+    location.dependency_dir = versioner_dir + "/dependencies";
     if (platform_dir.empty()) {
       platform_dir = versioner_dir + "/platforms";
     }
   } else {
-    if (!android::base::Realpath(argv[optind], &header_dir)) {
+    if (!android::base::Realpath(argv[optind], &location.header_dir)) {
       err(1, "failed to get realpath for path '%s'", argv[optind]);
     }
 
     if (argc - optind == 2) {
-      dependency_dir = argv[optind + 1];
+      location.dependency_dir = argv[optind + 1];
     }
   }
 
+  // Every file that lives in bits/fortify is logically a part of a header outside of bits/fortify.
+  // This makes the files there impossible to build on their own.
+  if (ignore_fortify_headers) {
+    std::string fortify_path = location.header_dir;
+    if (!android::base::EndsWith(location.header_dir, "/")) {
+      fortify_path += '/';
+    }
+    fortify_path += "bits/fortify";
+    location.ignored_directories.insert(std::move(fortify_path));
+  }
+
   if (selected_levels.empty()) {
     selected_levels = supported_levels;
   }
@@ -596,10 +622,10 @@
 
 
   struct stat st;
-  if (stat(header_dir.c_str(), &st) != 0) {
-    err(1, "failed to stat '%s'", header_dir.c_str());
+  if (const char *dir = location.header_dir.c_str(); stat(dir, &st) != 0) {
+    err(1, "failed to stat '%s'", dir);
   } else if (!S_ISDIR(st.st_mode)) {
-    errx(1, "'%s' is not a directory", header_dir.c_str());
+    errx(1, "'%s' is not a directory", dir);
   }
 
   std::set<CompilationType> compilation_types;
@@ -615,7 +641,7 @@
 
   auto start = std::chrono::high_resolution_clock::now();
   std::unique_ptr<HeaderDatabase> declaration_database =
-      compileHeaders(compilation_types, header_dir, dependency_dir);
+      compileHeaders(compilation_types, location);
   auto end = std::chrono::high_resolution_clock::now();
 
   if (verbose) {
@@ -625,7 +651,7 @@
 
   bool failed = false;
   if (dump) {
-    declaration_database->dump(header_dir + "/");
+    declaration_database->dump(location.header_dir + "/");
   } else {
     if (!sanityCheck(declaration_database.get())) {
       printf("versioner: sanity check failed\n");
@@ -641,7 +667,7 @@
   }
 
   if (!preprocessor_output_path.empty() && (force || !failed)) {
-    failed = !preprocessHeaders(preprocessor_output_path, header_dir, declaration_database.get());
+    failed = !preprocessHeaders(preprocessor_output_path, location.header_dir, declaration_database.get());
   }
   return failed;
 }