diff --git a/llvm/lib/Support/StringExtras.cpp b/llvm/lib/Support/StringExtras.cpp
--- a/llvm/lib/Support/StringExtras.cpp
+++ b/llvm/lib/Support/StringExtras.cpp
@@ -67,7 +67,7 @@
     else if (isPrint(C) && C != '"')
       Out << C;
     else
-      Out << '\\' << hexdigit(C >> 4) << hexdigit(C & 0x0F);
+      Out << "\\x" << hexdigit(C >> 4) << hexdigit(C & 0x0F);
   }
 }
 
diff --git a/llvm/unittests/ADT/StringExtrasTest.cpp b/llvm/unittests/ADT/StringExtrasTest.cpp
--- a/llvm/unittests/ADT/StringExtrasTest.cpp
+++ b/llvm/unittests/ADT/StringExtrasTest.cpp
@@ -124,7 +124,7 @@
   std::string str;
   raw_string_ostream OS(str);
   printEscapedString("ABCdef123&<>\\\"'\t", OS);
-  EXPECT_EQ("ABCdef123&<>\\\\\\22'\\09", OS.str());
+  EXPECT_EQ("ABCdef123&<>\\\\\\x22'\\x09", OS.str());
 }
 
 TEST(StringExtrasTest, printHTMLEscaped) {