Index: test/tools/llvm-cov/cov_dir.cpp
===================================================================
--- test/tools/llvm-cov/cov_dir.cpp
+++ test/tools/llvm-cov/cov_dir.cpp
@@ -0,0 +1,7 @@
+//RUN: rm -rf %t
+//RUN: mkdir -p %t/a/b/
+//RUN: echo "" > %t/a/b/c.tmp
+//RUN: echo "" > %t/a/d.tmp
+//RUN: llvm-cov show /dev/null -instr-profile=/dev/null -dump-input-file-list %t | FileCheck %s
+//CHECK-DAG: {{.*}}c.tmp
+//CHECK-DAG: {{.*}}d.tmp
Index: tools/llvm-cov/CodeCoverage.cpp
===================================================================
--- tools/llvm-cov/CodeCoverage.cpp
+++ tools/llvm-cov/CodeCoverage.cpp
@@ -70,6 +70,9 @@
   /// \brief Load the coverage mapping data. Return true if an error occured.
   std::unique_ptr<CoverageMapping> load();
 
+  /// \brief Collects all source files recursively inside the directory.
+  void collectSourceFiles(StringRef Path);
+
   int run(Command Cmd, int argc, const char **argv);
 
   typedef llvm::function_ref<int(int, const char **)> CommandLineParserType;
@@ -90,6 +93,7 @@
   bool CompareFilenamesOnly;
   StringMap<std::string> RemappedFilenames;
   std::string CoverageArch;
+  bool DumpFileNames;
 
 private:
   std::vector<std::string> CollectedPaths;
@@ -249,6 +253,34 @@
   return Coverage;
 }
 
+void CodeCoverageTool::collectSourceFiles(StringRef Path) {
+  if (CompareFilenamesOnly) {
+    addCollectedPath(Path.str());
+    return;
+  }
+  llvm::sys::fs::file_status Status;
+  llvm::sys::fs::status(Path, Status);
+  if (llvm::sys::fs::exists(Status)) {
+    // If it's a source file, collect it.
+    if (llvm::sys::fs::is_regular_file(Status)) {
+      addCollectedPath(Path.str());
+      return;
+    }
+    if (llvm::sys::fs::is_directory(Status)) {
+      std::error_code EC;
+      // Collect all source files within this directory by iterating
+      // recursively.
+      for (llvm::sys::fs::recursive_directory_iterator File(Path, EC), FileEnd;
+           File != FileEnd && !EC; File.increment(EC)) {
+        if (llvm::sys::fs::is_regular_file(File->path())) {
+          addCollectedPath(File->path());
+        }
+      }
+    }
+  } else
+    errs() << "Error: Can't access: " << Path.str().c_str() << "\n";
+}
+
 int CodeCoverageTool::run(Command Cmd, int argc, const char **argv) {
   cl::opt<std::string, true> ObjectFilename(
       cl::Positional, cl::Required, cl::location(this->ObjectFilename),
@@ -321,10 +353,15 @@
       "use-color", cl::desc("Emit colored output (default=autodetect)"),
       cl::init(cl::BOU_UNSET));
 
+  cl::opt<bool> DumpInputFileList(
+      "dump-input-file-list", cl::Optional,
+      cl::desc("Dump just filenames traversing into the directories."));
+
   auto commandLineParser = [&, this](int argc, const char **argv) -> int {
     cl::ParseCommandLineOptions(argc, argv, "LLVM code coverage tool\n");
     ViewOpts.Debug = DebugDump;
     CompareFilenamesOnly = FilenameEquivalence;
+    DumpFileNames = DumpInputFileList;
 
     ViewOpts.Format = Format;
     switch (ViewOpts.Format) {
@@ -379,8 +416,15 @@
           errs() << "error: " << File << ": " << EC.message();
           return 1;
         }
-      addCollectedPath(Path.str());
+      collectSourceFiles(Path.str());
     }
+
+    if (DumpFileNames) {
+      for (StringRef SF : SourceFiles)
+        outs() << SF << "\n";
+      return 0;
+    }
+
     return 0;
   };
 
@@ -432,6 +476,8 @@
   if (Err)
     return Err;
 
+  if (DumpFileNames)
+    return 0;
   ViewOpts.ShowLineNumbers = true;
   ViewOpts.ShowLineStats = ShowLineExecutionCounts.getNumOccurrences() != 0 ||
                            !ShowRegions || ShowBestLineRegionsCounts;
@@ -527,6 +573,8 @@
   if (Err)
     return Err;
 
+  if (DumpFileNames)
+    return 0;
   auto Coverage = load();
   if (!Coverage)
     return 1;