diff --git a/tools/versioner/src/Android.bp b/tools/versioner/src/Android.bp
index c5afa56..b86228f 100644
--- a/tools/versioner/src/Android.bp
+++ b/tools/versioner/src/Android.bp
@@ -1,6 +1,8 @@
 cc_binary_host {
     name: "versioner",
 
+    cpp_std: "gnu++17",
+
     srcs: [
         "versioner.cpp",
         "Arch.cpp",
@@ -29,6 +31,7 @@
         "-Wextra",
         "-Werror",
         "-Wno-unused-parameter",
+        "-fno-omit-frame-pointer",
 
         "-D__STDC_CONSTANT_MACROS",
         "-D__STDC_LIMIT_MACROS",
@@ -37,7 +40,6 @@
     target: {
         host: {
             cppflags: [
-                "-std=gnu++1z",
                 "-fno-rtti",
             ],
         },
diff --git a/tools/versioner/src/CompilationType.cpp b/tools/versioner/src/CompilationType.cpp
index e9d31cb..7e7bb5d 100644
--- a/tools/versioner/src/CompilationType.cpp
+++ b/tools/versioner/src/CompilationType.cpp
@@ -21,6 +21,7 @@
 
 std::string to_string(const CompilationType& type) {
   std::stringstream ss;
-  ss << to_string(type.arch) << "-" << type.api_level << " [fob = " << type.file_offset_bits << "]";
+  ss << to_string(type.arch) << "-" << type.api_level << " [" << (type.cpp ? "c++" : "c")
+     << ", fob = " << type.file_offset_bits << "]";
   return ss.str();
 }
diff --git a/tools/versioner/src/CompilationType.h b/tools/versioner/src/CompilationType.h
index 7d516b2..2f4cf5c 100644
--- a/tools/versioner/src/CompilationType.h
+++ b/tools/versioner/src/CompilationType.h
@@ -25,12 +25,13 @@
 
 struct CompilationType {
   Arch arch;
+  bool cpp;
   int api_level;
   int file_offset_bits;
 
  private:
   auto tie() const {
-    return std::tie(arch, api_level, file_offset_bits);
+    return std::tie(arch, cpp, api_level, file_offset_bits);
   }
 
  public:
@@ -49,11 +50,13 @@
   size_t operator()(CompilationType type) const {
     struct {
       int32_t arch : 3;
+      int32_t cpp : 1;
       int32_t api_level : 6;
       int32_t file_offset_bits : 1;
-      int32_t padding : 22;
+      int32_t padding : 21;
     } packed;
     packed.arch = static_cast<int32_t>(type.arch);
+    packed.cpp = type.cpp;
     packed.api_level = type.api_level;
     packed.file_offset_bits = (type.file_offset_bits == 64);
     packed.padding = 0;
diff --git a/tools/versioner/src/DeclarationDatabase.cpp b/tools/versioner/src/DeclarationDatabase.cpp
index aef4f55..4443834 100644
--- a/tools/versioner/src/DeclarationDatabase.cpp
+++ b/tools/versioner/src/DeclarationDatabase.cpp
@@ -35,6 +35,22 @@
 
 using namespace clang;
 
+static bool shouldMangle(MangleContext* mangler, NamedDecl* decl) {
+  // Passing a decl with static linkage to the mangler gives incorrect results.
+  // Check some things ourselves before handing it off to the mangler.
+  if (auto FD = dyn_cast<FunctionDecl>(decl)) {
+    if (FD->isExternC()) {
+      return false;
+    }
+
+    if (FD->isInExternCContext()) {
+      return false;
+    }
+  }
+
+  return mangler->shouldMangleDeclName(decl);
+}
+
 class Visitor : public RecursiveASTVisitor<Visitor> {
   HeaderDatabase& database;
   CompilationType type;
@@ -54,9 +70,14 @@
       }
     }
 
+    // <math.h> maps fool onto foo on 32-bit, since long double is the same as double.
+    if (auto asm_attr = decl->getAttr<AsmLabelAttr>()) {
+      return asm_attr->getLabel();
+    }
+
     // The decl might not have a name (e.g. bitfields).
     if (auto identifier = decl->getIdentifier()) {
-      if (mangler->shouldMangleDeclName(decl)) {
+      if (shouldMangle(mangler.get(), decl)) {
         std::string mangled;
         llvm::raw_string_ostream ss(mangled);
         mangler->mangleName(decl, ss);
diff --git a/tools/versioner/src/Driver.cpp b/tools/versioner/src/Driver.cpp
index 8a8e00a..8911190 100644
--- a/tools/versioner/src/Driver.cpp
+++ b/tools/versioner/src/Driver.cpp
@@ -98,9 +98,16 @@
                                    CompilationType type,
                                    const std::vector<std::string>& include_dirs) {
   std::vector<std::string> cmd = { "versioner" };
-  cmd.push_back("-std=c11");
-  cmd.push_back("-x");
-  cmd.push_back("c");
+  if (type.cpp) {
+    cmd.push_back("-std=gnu++11");
+    cmd.push_back("-x");
+    cmd.push_back("c++");
+  } else {
+    cmd.push_back("-std=gnu11");
+    cmd.push_back("-x");
+    cmd.push_back("c");
+  }
+
   cmd.push_back("-fsyntax-only");
 
   cmd.push_back("-Wall");
diff --git a/tools/versioner/src/versioner.cpp b/tools/versioner/src/versioner.cpp
index 83b4027..a082f07 100644
--- a/tools/versioner/src/versioner.cpp
+++ b/tools/versioner/src/versioner.cpp
@@ -36,6 +36,7 @@
 #include <set>
 #include <sstream>
 #include <string>
+#include <string_view>
 #include <thread>
 #include <unordered_map>
 #include <vector>
@@ -82,18 +83,28 @@
 
 namespace {
 struct HeaderLocationInformation {
-  std::string header_dir;
+  std::string header_path;
   std::string dependency_dir;
   // Absolute paths to ignore all children -- including subdirectories -- of.
   std::unordered_set<std::string> ignored_directories;
 };
 }
 
+static bool is_dir(const std::string& path) {
+  struct stat st;
+  return stat(path.c_str(), &st) == 0 && S_ISDIR(st.st_mode);
+}
+
 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 };
+      collectHeaders(location.header_path, location.ignored_directories);
+  std::vector<std::string> dependencies;
+
+  if (is_dir(location.header_path)) {
+    dependencies.emplace_back(location.header_path);
+  }
+
   if (!location.dependency_dir.empty()) {
     auto collect_children = [&dependencies](const std::string& dir_path) {
       DIR* dir = opendir(dir_path.c_str());
@@ -159,10 +170,12 @@
       }
 
       for (int file_offset_bits : { 32, 64 }) {
-        CompilationType type = {
-          .arch = arch, .api_level = api_level, .file_offset_bits = file_offset_bits
-        };
-        result.insert(type);
+        for (bool cpp : { true, false }) {
+          CompilationType type = {
+            .arch = arch, .cpp = cpp, .api_level = api_level, .file_offset_bits = file_offset_bits
+          };
+          result.insert(type);
+        }
       }
     }
   }
@@ -175,7 +188,7 @@
     errx(1, "compileHeaders received no CompilationTypes");
   }
 
-  auto vfs = createCommonVFS(location.header_dir, location.dependency_dir, add_include);
+  auto vfs = createCommonVFS(location.header_path, location.dependency_dir, add_include);
 
   size_t thread_count = max_thread_count;
   std::vector<std::thread> threads;
@@ -282,7 +295,8 @@
       for (const auto& inline_def_it : inline_definitions) {
         auto intersection = Intersection(compilation_types, inline_def_it.second);
         if (!intersection.empty()) {
-          fprintf(stderr, "versioner: conflicting inline definitions:\n");
+          fprintf(stderr, "versioner: conflicting inline definitions for symbol %s:\n",
+                  symbol.name.c_str());
           fprintf(stderr, "  declarations visible in: %s\n", Join(intersection, ", ").c_str());
           decl->dump(cwd, stderr, 4);
           inline_def_it.first->dump(cwd, stderr, 4);
@@ -526,8 +540,8 @@
         if (stat(platform_dir.c_str(), &st) != 0) {
           err(1, "failed to stat platform directory '%s'", platform_dir.c_str());
         }
-        if (!S_ISDIR(st.st_mode)) {
-          errx(1, "'%s' is not a directory", optarg);
+        if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode)) {
+          errx(1, "'%s' is not a file or directory", optarg);
         }
         break;
       }
@@ -598,13 +612,13 @@
   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";
-    location.header_dir = versioner_dir + "/current";
+    location.header_path = 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], &location.header_dir)) {
+    if (!android::base::Realpath(argv[optind], &location.header_path)) {
       err(1, "failed to get realpath for path '%s'", argv[optind]);
     }
 
@@ -616,8 +630,8 @@
   // 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, "/")) {
+    std::string fortify_path = location.header_path;
+    if (!android::base::EndsWith(location.header_path, "/")) {
       fortify_path += '/';
     }
     fortify_path += "bits/fortify";
@@ -634,10 +648,8 @@
 
 
   struct stat st;
-  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", dir);
+  if (const char *path = location.header_path.c_str(); stat(path, &st) != 0) {
+    err(1, "failed to stat '%s'", path);
   }
 
   std::set<CompilationType> compilation_types;
@@ -663,7 +675,7 @@
 
   bool failed = false;
   if (dump) {
-    declaration_database->dump(location.header_dir + "/");
+    declaration_database->dump(location.header_path + "/");
   } else {
     if (!sanityCheck(declaration_database.get())) {
       printf("versioner: sanity check failed\n");
@@ -679,7 +691,8 @@
   }
 
   if (!preprocessor_output_path.empty() && (force || !failed)) {
-    failed = !preprocessHeaders(preprocessor_output_path, location.header_dir, declaration_database.get());
+    failed = !preprocessHeaders(preprocessor_output_path, location.header_path,
+                                declaration_database.get());
   }
   return failed;
 }
diff --git a/tools/versioner/tests/extern_cpp/headers/string.h b/tools/versioner/tests/extern_cpp/headers/string.h
new file mode 100644
index 0000000..5ac43ac
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp/headers/string.h
@@ -0,0 +1,18 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#define __RENAME(x) __asm__(#x)
+
+#if defined(__cplusplus)
+extern "C++" char* basename(char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+extern "C++" const char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#else
+char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#endif
+
+char* foo() __INTRODUCED_IN(8);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/extern_cpp/platforms/android-21/arch-arm/symbols/libc.so.functions.txt b/tools/versioner/tests/extern_cpp/platforms/android-21/arch-arm/symbols/libc.so.functions.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp/platforms/android-21/arch-arm/symbols/libc.so.functions.txt
@@ -0,0 +1 @@
+
diff --git a/tools/versioner/tests/extern_cpp/platforms/android-23/arch-arm/symbols/libc.so.functions.txt b/tools/versioner/tests/extern_cpp/platforms/android-23/arch-arm/symbols/libc.so.functions.txt
new file mode 100644
index 0000000..36fe04f
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp/platforms/android-23/arch-arm/symbols/libc.so.functions.txt
@@ -0,0 +1 @@
+__gnu_basename
diff --git a/tools/versioner/tests/extern_cpp/run.sh b/tools/versioner/tests/extern_cpp/run.sh
new file mode 100644
index 0000000..e320c95
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp/run.sh
@@ -0,0 +1 @@
+versioner headers -p platforms -r arm -a 21 -a 23 -i
diff --git a/tools/versioner/tests/extern_cpp_mismatch/headers/string.h b/tools/versioner/tests/extern_cpp_mismatch/headers/string.h
new file mode 100644
index 0000000..66133d8
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp_mismatch/headers/string.h
@@ -0,0 +1,16 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#define __RENAME(x) __asm__(#x)
+
+#if defined(__cplusplus)
+extern "C++" char* basename(char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+extern "C++" const char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#else
+char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/extern_cpp_mismatch/platforms/android-9/arch-arm/symbols/libc.so.functions.txt b/tools/versioner/tests/extern_cpp_mismatch/platforms/android-9/arch-arm/symbols/libc.so.functions.txt
new file mode 100644
index 0000000..257cc56
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp_mismatch/platforms/android-9/arch-arm/symbols/libc.so.functions.txt
@@ -0,0 +1 @@
+foo
diff --git a/tools/versioner/tests/extern_cpp_mismatch/run.sh b/tools/versioner/tests/extern_cpp_mismatch/run.sh
new file mode 100644
index 0000000..a34fda8
--- /dev/null
+++ b/tools/versioner/tests/extern_cpp_mismatch/run.sh
@@ -0,0 +1 @@
+versioner headers -p platforms -r arm -a 9 -i
\ No newline at end of file
diff --git a/tools/versioner/tests/multiple_definition/expected_fail b/tools/versioner/tests/multiple_definition/expected_fail
index 7070390..cb4acc6 100644
--- a/tools/versioner/tests/multiple_definition/expected_fail
+++ b/tools/versioner/tests/multiple_definition/expected_fail
@@ -1,5 +1,5 @@
-versioner: conflicting inline definitions:
-  declarations visible in: arm-9 [fob = 32], arm-9 [fob = 64], arm-12 [fob = 32], arm-12 [fob = 64]
+versioner: conflicting inline definitions for symbol foo:
+  declarations visible in: arm-9 [c, fob = 32], arm-9 [c, fob = 64], arm-12 [c, fob = 32], arm-12 [c, fob = 64], arm-9 [c++, fob = 32], arm-9 [c++, fob = 64], arm-12 [c++, fob = 32], arm-12 [c++, fob = 64]
     static definition @ headers/foo.h:5:1
       no availability
     static definition @ headers/bar.h:5:1
diff --git a/tools/versioner/tests/unnamed_bitfield/headers/foo.h b/tools/versioner/tests/unnamed_bitfield/headers/foo.h
new file mode 100644
index 0000000..58686c3
--- /dev/null
+++ b/tools/versioner/tests/unnamed_bitfield/headers/foo.h
@@ -0,0 +1,8 @@
+// <sys/timex.h> was causing a segfault when compiled in C++ mode because
+// versioner was trying to mangle the name of an unnamed bitfield.
+struct foo {
+  int : 32;
+  int : 32;
+  int : 32;
+  int : 32;
+};
diff --git a/tools/versioner/tests/unnamed_bitfield/platforms/android-9/arch-arm/symbols/libc.so.functions.txt b/tools/versioner/tests/unnamed_bitfield/platforms/android-9/arch-arm/symbols/libc.so.functions.txt
new file mode 100644
index 0000000..257cc56
--- /dev/null
+++ b/tools/versioner/tests/unnamed_bitfield/platforms/android-9/arch-arm/symbols/libc.so.functions.txt
@@ -0,0 +1 @@
+foo
diff --git a/tools/versioner/tests/unnamed_bitfield/run.sh b/tools/versioner/tests/unnamed_bitfield/run.sh
new file mode 100644
index 0000000..a34fda8
--- /dev/null
+++ b/tools/versioner/tests/unnamed_bitfield/run.sh
@@ -0,0 +1 @@
+versioner headers -p platforms -r arm -a 9 -i
\ No newline at end of file