Index: llvm/trunk/lib/Support/Path.cpp
===================================================================
--- llvm/trunk/lib/Support/Path.cpp
+++ llvm/trunk/lib/Support/Path.cpp
@@ -726,6 +726,10 @@
   SmallString<256> buffer = path::root_path(path, style);
   for (StringRef C : components)
     path::append(buffer, style, C);
+  // If the buffer is empty, then return ".". Many other path utilities
+  // do this so it seems to be an expected result.
+  if (buffer.empty())
+    buffer.append(1, '.');
   return buffer;
 }
 
Index: llvm/trunk/unittests/Support/Path.cpp
===================================================================
--- llvm/trunk/unittests/Support/Path.cpp
+++ llvm/trunk/unittests/Support/Path.cpp
@@ -1146,7 +1146,7 @@
 TEST(Support, RemoveDots) {
   EXPECT_EQ("foolz\\wat",
             remove_dots(".\\.\\\\foolz\\wat", false, path::Style::windows));
-  EXPECT_EQ("", remove_dots(".\\\\\\\\\\", false, path::Style::windows));
+  EXPECT_EQ(".", remove_dots(".\\\\\\\\\\", false, path::Style::windows));
 
   EXPECT_EQ("a\\..\\b\\c",
             remove_dots(".\\a\\..\\b\\c", false, path::Style::windows));
@@ -1163,7 +1163,8 @@
 
   EXPECT_EQ("foolz/wat",
             remove_dots("././/foolz/wat", false, path::Style::posix));
-  EXPECT_EQ("", remove_dots("./////", false, path::Style::posix));
+  EXPECT_EQ(".", remove_dots("./////", false, path::Style::posix));
+  EXPECT_EQ(".", remove_dots("", false, path::Style::posix));
 
   EXPECT_EQ("a/../b/c", remove_dots("./a/../b/c", false, path::Style::posix));
   EXPECT_EQ("b/c", remove_dots("./a/../b/c", true, path::Style::posix));