diff --git a/llvm/include/llvm/Support/GraphWriter.h b/llvm/include/llvm/Support/GraphWriter.h
--- a/llvm/include/llvm/Support/GraphWriter.h
+++ b/llvm/include/llvm/Support/GraphWriter.h
@@ -318,6 +318,9 @@
   return O;
 }
 
+static std::string replace_illegal_filename_chars(std::string filename,
+                                                  const char replacement_char);
+
 std::string createGraphFilename(const Twine &Name, int &FD);
 
 /// Writes graph into a provided {@code Filename}.
diff --git a/llvm/lib/Support/GraphWriter.cpp b/llvm/lib/Support/GraphWriter.cpp
--- a/llvm/lib/Support/GraphWriter.cpp
+++ b/llvm/lib/Support/GraphWriter.cpp
@@ -76,10 +76,32 @@
   return Colors[ColorNumber % NumColors];
 }
 
+static std::string
+llvm::replace_illegal_filename_chars(std::string filename,
+                                     const char replacement_char) {
+#ifdef _WIN32
+  std::string illegalChars = "\\/:?\"<>|";
+#else
+  std::string illegalChars = "/";
+#endif
+
+  for (std::string::iterator it = illegalChars.begin(); it < illegalChars.end();
+       ++it) {
+    std::replace(filename.begin(), filename.end(), *it, replacement_char);
+  }
+
+  return filename;
+}
+
 std::string llvm::createGraphFilename(const Twine &Name, int &FD) {
   FD = -1;
   SmallString<128> Filename;
-  std::error_code EC = sys::fs::createTemporaryFile(Name, "dot", FD, Filename);
+
+  // Replace illegal characters in graph filename with '_' if needed
+  std::string CleansedName = replace_illegal_filename_chars(Name.str(), '_');
+
+  std::error_code EC =
+      sys::fs::createTemporaryFile(CleansedName, "dot", FD, Filename);
   if (EC) {
     errs() << "Error: " << EC.message() << "\n";
     return "";