Index: include/llvm/ADT/StringRef.h
===================================================================
--- include/llvm/ADT/StringRef.h
+++ include/llvm/ADT/StringRef.h
@@ -90,6 +90,11 @@
     /*implicit*/ constexpr StringRef(const char *data, size_t length)
         : Data(data), Length(length) {}
 
+    /// Construct a string ref from a pointer to bytes and length.
+    LLVM_ATTRIBUTE_ALWAYS_INLINE
+    /*implicit*/ constexpr StringRef(const unsigned char *data, size_t length)
+        : Data(reinterpret_cast<const char *>(data)), Length(length) {}
+
     /// Construct a string ref from an std::string.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
     /*implicit*/ StringRef(const std::string &Str)
Index: test/tools/llvm-strings/negative.test
===================================================================
--- test/tools/llvm-strings/negative.test
+++ test/tools/llvm-strings/negative.test
@@ -0,0 +1 @@
+# RUN: echo -e \x80 | llvm-strings -
Index: tools/llvm-strings/llvm-strings.cpp
===================================================================
--- tools/llvm-strings/llvm-strings.cpp
+++ tools/llvm-strings/llvm-strings.cpp
@@ -77,9 +77,10 @@
     OS << " " << L << '\n';
   };
 
-  const char *B = Contents.begin();
-  const char *P = nullptr, *E = nullptr, *S = nullptr;
-  for (P = Contents.begin(), E = Contents.end(); P < E; ++P) {
+  const unsigned char *B = Contents.bytes_begin();
+  const unsigned char *E = Contents.bytes_end();
+  const unsigned char *S = nullptr;
+  for (const unsigned char *P = B; P < E; ++P) {
     if (std::isgraph(*P) || std::isblank(*P)) {
       if (S == nullptr)
         S = P;