diff --git a/simpleperf/cmd_report_sample.cpp b/simpleperf/cmd_report_sample.cpp
index 897f5ef..b2ae8e4 100644
--- a/simpleperf/cmd_report_sample.cpp
+++ b/simpleperf/cmd_report_sample.cpp
@@ -89,6 +89,7 @@
 "--remove-unknown-kernel-symbols  Remove kernel callchains when kernel symbols\n"
 "                                 are not available in perf.data.\n"
 "--show-art-frames  Show frames of internal methods in the ART Java interpreter.\n"
+"--symdir <dir>     Look for files with symbols in a directory recursively.\n"
             // clang-format on
             ),
         record_filename_("perf.data"),
@@ -261,6 +262,13 @@
       remove_unknown_kernel_symbols_ = true;
     } else if (args[i] == "--show-art-frames") {
       show_art_frames_ = true;
+    } else if (args[i] == "--symdir") {
+      if (!NextArgumentOrError(args, &i)) {
+        return false;
+      }
+      if (!Dso::AddSymbolDir(args[i])) {
+        return false;
+      }
     } else {
       ReportUnknownOption(args, i);
       return false;
diff --git a/simpleperf/cmd_report_sample_test.cpp b/simpleperf/cmd_report_sample_test.cpp
index f298cfb..a393713 100644
--- a/simpleperf/cmd_report_sample_test.cpp
+++ b/simpleperf/cmd_report_sample_test.cpp
@@ -152,3 +152,12 @@
   ASSERT_NE(data.find("mangled_symbol: _ZN7android8hardware14IPCThreadState14talkWithDriverEb"),
             std::string::npos);
 }
+
+TEST(cmd_report_sample, symdir_option) {
+  std::string data;
+  GetProtobufReport(PERF_DATA_FOR_BUILD_ID_CHECK, &data);
+  ASSERT_EQ(data.find("symbol: main"), std::string::npos);
+  GetProtobufReport(PERF_DATA_FOR_BUILD_ID_CHECK, &data,
+                    {"--symdir", GetTestDataDir() + CORRECT_SYMFS_FOR_BUILD_ID_CHECK});
+  ASSERT_NE(data.find("symbol: main"), std::string::npos);
+}
diff --git a/simpleperf/dso.cpp b/simpleperf/dso.cpp
index a9c86f4..8e641a8 100644
--- a/simpleperf/dso.cpp
+++ b/simpleperf/dso.cpp
@@ -55,20 +55,46 @@
     }
   }
   symfs_dir_ = dirname;
-  build_id_to_file_map_.clear();
   std::string build_id_list_file = symfs_dir_ + "build_id_list";
   std::string build_id_list;
   if (android::base::ReadFileToString(build_id_list_file, &build_id_list)) {
     for (auto& line : android::base::Split(build_id_list, "\n")) {
       std::vector<std::string> items = android::base::Split(line, "=");
       if (items.size() == 2u) {
-        build_id_to_file_map_[items[0]] = items[1];
+        build_id_to_file_map_[items[0]] = symfs_dir_ + items[1];
       }
     }
   }
   return true;
 }
 
+bool DebugElfFileFinder::AddSymbolDir(const std::string& symbol_dir) {
+  if (!IsDir(symbol_dir)) {
+    LOG(ERROR) << "Invalid symbol dir " << symbol_dir;
+    return false;
+  }
+  std::string dir = symbol_dir;
+  if (dir.size() > 1 && dir.back() == '/') {
+    dir.pop_back();
+  }
+  CollectBuildIdInDir(dir);
+  return true;
+}
+
+void DebugElfFileFinder::CollectBuildIdInDir(const std::string& dir) {
+  for (const std::string& entry : GetEntriesInDir(dir)) {
+    std::string path = dir + "/" + entry;
+    if (IsDir(path)) {
+      CollectBuildIdInDir(path);
+    } else {
+      BuildId build_id;
+      if (GetBuildIdFromElfFile(path, &build_id) == ElfStatus::NO_ERROR) {
+        build_id_to_file_map_[build_id.ToString()] = path;
+      }
+    }
+  }
+}
+
 void DebugElfFileFinder::SetVdsoFile(const std::string& vdso_file, bool is_64bit) {
   if (is_64bit) {
     vdso_64bit_ = vdso_file;
@@ -85,36 +111,37 @@
     } else if (!force_64bit && !vdso_32bit_.empty()) {
       return vdso_32bit_;
     }
-  } else if (!symfs_dir_.empty()) {
+  }
+  // 1. Try build_id_to_file_map.
+  if (!build_id_to_file_map_.empty()) {
     if (!build_id.IsEmpty() || GetBuildIdFromDsoPath(dso_path, &build_id)) {
-      std::string result;
-      auto check_path = [&](const std::string& path) {
-        BuildId debug_build_id;
-        if (GetBuildIdFromDsoPath(path, &debug_build_id) && debug_build_id == build_id) {
-          result = path;
-          return true;
-        }
-        return false;
-      };
-
-      // 1. Try build_id_to_file_map.
       auto it = build_id_to_file_map_.find(build_id.ToString());
       if (it != build_id_to_file_map_.end()) {
-        if (check_path(symfs_dir_ + it->second)) {
-          return result;
-        }
-      }
-      // 2. Try concatenating symfs_dir and dso_path.
-      if (check_path(symfs_dir_ + dso_path)) {
-        return result;
-      }
-      // 3. Try concatenating /usr/lib/debug and dso_path.
-      // Linux host can store debug shared libraries in /usr/lib/debug.
-      if (check_path("/usr/lib/debug" + dso_path)) {
-        return result;
+        return it->second;
       }
     }
   }
+  auto check_path = [&](const std::string& path) {
+    BuildId debug_build_id;
+    if (GetBuildIdFromDsoPath(path, &debug_build_id)) {
+      if (!build_id.IsEmpty() || GetBuildIdFromDsoPath(dso_path, &build_id)) {
+        if (build_id == debug_build_id) {
+          return true;
+        }
+      }
+    }
+    return false;
+  };
+
+  // 2. Try concatenating symfs_dir and dso_path.
+  if (!symfs_dir_.empty() && check_path(symfs_dir_ + dso_path)) {
+    return symfs_dir_ + dso_path;
+  }
+  // 3. Try concatenating /usr/lib/debug and dso_path.
+  // Linux host can store debug shared libraries in /usr/lib/debug.
+  if (check_path("/usr/lib/debug" + dso_path)) {
+    return "/usr/lib/debug" + dso_path;
+  }
   return dso_path;
 }
 }  // namespace simpleperf_dso_imp
@@ -184,6 +211,10 @@
   return debug_elf_file_finder_.SetSymFsDir(symfs_dir);
 }
 
+bool Dso::AddSymbolDir(const std::string& symbol_dir) {
+  return debug_elf_file_finder_.AddSymbolDir(symbol_dir);
+}
+
 void Dso::SetVmlinux(const std::string& vmlinux) { vmlinux_ = vmlinux; }
 
 void Dso::SetBuildIds(
diff --git a/simpleperf/dso.h b/simpleperf/dso.h
index 4bd0779..83f4f65 100644
--- a/simpleperf/dso.h
+++ b/simpleperf/dso.h
@@ -36,11 +36,14 @@
  public:
   void Reset();
   bool SetSymFsDir(const std::string& symfs_dir);
+  bool AddSymbolDir(const std::string& symbol_dir);
   void SetVdsoFile(const std::string& vdso_file, bool is_64bit);
   std::string FindDebugFile(const std::string& dso_path, bool force_64bit,
                             BuildId& build_id);
 
  private:
+  void CollectBuildIdInDir(const std::string& dir);
+
   std::string vdso_64bit_;
   std::string vdso_32bit_;
   std::string symfs_dir_;
@@ -110,7 +113,13 @@
  public:
   static void SetDemangle(bool demangle);
   static std::string Demangle(const std::string& name);
+  // SymFsDir is used to provide an alternative root directory looking for files with symbols.
+  // For example, if we are searching symbols for /system/lib/libc.so and SymFsDir is /data/symbols,
+  // then we will also search file /data/symbols/system/lib/libc.so.
   static bool SetSymFsDir(const std::string& symfs_dir);
+  // SymbolDir is used to add a directory containing files with symbols. Each file under it will
+  // be searched recursively to build a build_id_map.
+  static bool AddSymbolDir(const std::string& symbol_dir);
   static void SetVmlinux(const std::string& vmlinux);
   static void SetKallsyms(std::string kallsyms) {
     if (!kallsyms.empty()) {
diff --git a/simpleperf/dso_test.cpp b/simpleperf/dso_test.cpp
index a1d005a..ab220a1 100644
--- a/simpleperf/dso_test.cpp
+++ b/simpleperf/dso_test.cpp
@@ -67,6 +67,15 @@
   ASSERT_EQ(finder.FindDebugFile("[vdso]", true, build_id), fake_vdso64);
 }
 
+TEST(DebugElfFileFinder, add_symbol_dir) {
+  DebugElfFileFinder finder;
+  ASSERT_FALSE(finder.AddSymbolDir(GetTestDataDir() + "dir_not_exist"));
+  ASSERT_EQ(finder.FindDebugFile("elf", false, CHECK_ELF_FILE_BUILD_ID), "elf");
+  ASSERT_TRUE(finder.AddSymbolDir(GetTestDataDir() + CORRECT_SYMFS_FOR_BUILD_ID_CHECK));
+  ASSERT_EQ(finder.FindDebugFile("elf", false, CHECK_ELF_FILE_BUILD_ID),
+            GetTestDataDir() + CORRECT_SYMFS_FOR_BUILD_ID_CHECK + "/elf_for_build_id_check");
+}
+
 TEST(dso, dex_file_dso) {
 #if defined(__linux__)
   for (DsoType dso_type : {DSO_DEX_FILE, DSO_ELF_FILE}) {
diff --git a/simpleperf/environment.cpp b/simpleperf/environment.cpp
index b90606b..4962e7d 100644
--- a/simpleperf/environment.cpp
+++ b/simpleperf/environment.cpp
@@ -761,7 +761,8 @@
     s.clear();
   }
   for (size_t i = 0; i < s.size(); ++i) {
-    if (isspace(s[i])) {
+    // /proc/pid/cmdline uses 0 to separate arguments.
+    if (isspace(s[i]) || s[i] == 0) {
       s.resize(i);
       break;
     }
diff --git a/simpleperf/get_test_data.h b/simpleperf/get_test_data.h
index 114b645..67bf0ea 100644
--- a/simpleperf/get_test_data.h
+++ b/simpleperf/get_test_data.h
@@ -97,6 +97,8 @@
 static const std::string SYMFS_FOR_NO_SYMBOL_TABLE_WARNING = "data/symfs_for_no_symbol_table_warning";
 static const std::string SYMFS_FOR_READ_ELF_FILE_WARNING = "data/symfs_for_read_elf_file_warning";
 
+static BuildId CHECK_ELF_FILE_BUILD_ID("91b1c10fdd9fe2221dfec525497637f2229bfdbb");
+
 // generated_by_linux_perf.data is generated by `perf record -F 1 -a -g -- sleep 0.1`.
 static const std::string PERF_DATA_GENERATED_BY_LINUX_PERF = "generated_by_linux_perf.data";