Index: include/clang/Tooling/CommonOptionsParser.h
===================================================================
--- include/clang/Tooling/CommonOptionsParser.h
+++ include/clang/Tooling/CommonOptionsParser.h
@@ -72,6 +72,22 @@
   /// This constructor exits program in case of error.
   CommonOptionsParser(int &argc, const char **argv,
                       llvm::cl::OptionCategory &Category,
+                      const char *Overview = nullptr)
+    : CommonOptionsParser (argc, argv, Category, llvm::cl::OneOrMore, Overview) {}
+
+  /// \brief Parses command-line, initializes a compilation database.
+  ///
+  /// This constructor can change argc and argv contents, e.g. consume
+  /// command-line options used for creating FixedCompilationDatabase.
+  ///
+  /// All options not belonging to \p Category become hidden.
+  ///
+  /// I also allows calls to set the required number of positional parameters.
+  ///
+  /// This constructor exits program in case of error.
+  CommonOptionsParser(int &argc, const char **argv,
+                      llvm::cl::OptionCategory &Category,
+                      enum llvm::cl::NumOccurrencesFlag OccurrencesFlag,
                       const char *Overview = nullptr);
 
   /// Returns a reference to the loaded compilations database.
Index: lib/Tooling/CommonOptionsParser.cpp
===================================================================
--- lib/Tooling/CommonOptionsParser.cpp
+++ lib/Tooling/CommonOptionsParser.cpp
@@ -94,6 +94,7 @@
 
 CommonOptionsParser::CommonOptionsParser(int &argc, const char **argv,
                                          cl::OptionCategory &Category,
+                                         enum llvm::cl::NumOccurrencesFlag OccurrencesFlag,
                                          const char *Overview) {
   static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden);
 
@@ -101,7 +102,7 @@
                                         cl::Optional, cl::cat(Category));
 
   static cl::list<std::string> SourcePaths(
-      cl::Positional, cl::desc("<source0> [... <sourceN>]"), cl::OneOrMore,
+      cl::Positional, cl::desc("<source0> [... <sourceN>]"), OccurrencesFlag,
       cl::cat(Category));
 
   static cl::list<std::string> ArgsAfter(
@@ -120,6 +121,8 @@
                                                                    argv));
   cl::ParseCommandLineOptions(argc, argv, Overview);
   SourcePathList = SourcePaths;
+  if (OccurrencesFlag == cl::ZeroOrMore && SourcePathList.empty())
+    return;
   if (!Compilations) {
     std::string ErrorMessage;
     if (!BuildPath.empty()) {