Index: clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
===================================================================
--- clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
+++ clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
@@ -73,6 +73,14 @@
 )"),
                                    cl::init(""), cl::cat(ClangTidyCategory));
 
+static cl::opt<std::string> ConfigFile("config-file", cl::desc(R"(
+Specify full path of .clang-tidy or custom config file.
+For example, --config-file=/some/path/myTidyConfig
+Note: this option is mutually exclusive to --config and --checks options.
+)"),
+                                       cl::init(""),
+                                       cl::cat(ClangTidyCategory));
+
 static cl::opt<std::string> WarningsAsErrors("warnings-as-errors", cl::desc(R"(
 Upgrades warnings to errors. Same format as
 '-checks'.
@@ -279,6 +287,7 @@
 
   ClangTidyOptions DefaultOptions;
   DefaultOptions.Checks = DefaultChecks;
+  DefaultOptions.ConfigFile = "";
   DefaultOptions.WarningsAsErrors = "";
   DefaultOptions.HeaderFilterRegex = HeaderFilter;
   DefaultOptions.SystemHeaders = SystemHeaders;
@@ -291,6 +300,8 @@
   ClangTidyOptions OverrideOptions;
   if (Checks.getNumOccurrences() > 0)
     OverrideOptions.Checks = Checks;
+  if (ConfigFile.getNumOccurrences() > 0)
+    OverrideOptions.ConfigFile = ConfigFile;
   if (WarningsAsErrors.getNumOccurrences() > 0)
     OverrideOptions.WarningsAsErrors = WarningsAsErrors;
   if (HeaderFilter.getNumOccurrences() > 0)
@@ -302,6 +313,30 @@
   if (UseColor.getNumOccurrences() > 0)
     OverrideOptions.UseColor = UseColor;
 
+  if (!ConfigFile.empty()) {
+    if (!Config.empty()) {
+      llvm::errs() << "Error: --config-file and --config are mutually "
+                      "exclusive. Specify only one.\n";
+      return nullptr;
+    }
+
+    if (!Checks.empty()) {
+      llvm::errs() << "Error: --config-file and --checks are mutually "
+                      "exclusive. Specify only one.\n";
+      return nullptr;
+    }
+
+    llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
+        llvm::MemoryBuffer::getFile(ConfigFile.c_str());
+    if (std::error_code EC = Text.getError()) {
+      llvm::errs() << "Can't read config-file '" << ConfigFile
+                   << "': " << EC.message() << "\n";
+      return nullptr;
+    }
+
+    Config.assign((*Text)->getBuffer());
+  }
+
   if (!Config.empty()) {
     if (llvm::ErrorOr<ClangTidyOptions> ParsedConfig =
             parseConfiguration(Config)) {
Index: clang-tools-extra/test/clang-tidy/infrastructure/config-file.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/infrastructure/config-file.cpp
@@ -0,0 +1,12 @@
+// REQUIRES: shell
+// RUN: mkdir -p %T/config-file/
+// RUN: cp %s %T/read-file-config/test.cpp
+// RUN: echo 'Checks: "-*,hicpp-uppercase-literal-suffix"' > %T/read-file-config/.clang-tidy
+// RUN: clang-tidy --config-file=%T/read-file-config/.clang-tidy %T/read-file-config/test.cpp | grep "warning: .*\[hicpp-uppercase-literal-suffix\]$"
+
+void f() {
+  unsigned long c = 100ull;
+  int x;
+  x = 1;
+  x = 2;
+}