Index: lib/Support/GlobPattern.cpp
===================================================================
--- lib/Support/GlobPattern.cpp
+++ lib/Support/GlobPattern.cpp
@@ -36,24 +36,24 @@
     // If it doesn't start with something like X-Y,
     // consume the first character and proceed.
     if (S[1] != '-') {
-      BV[S[0]] = true;
+      BV[(uint8_t)S[0]] = true;
       S = S.substr(1);
       continue;
     }
 
     // It must be in the form of X-Y.
     // Validate it and then interpret the range.
-    if (S[0] > S[2])
+    if ((uint8_t)S[0] > (uint8_t)S[2])
       return make_error<StringError>("invalid glob pattern: " + Original,
                                      errc::invalid_argument);
 
-    for (int C = S[0]; C <= S[2]; ++C)
-      BV[C] = true;
+    for (int C = (uint8_t)S[0]; C <= (uint8_t)S[2]; ++C)
+      BV[(uint8_t)C] = true;
     S = S.substr(3);
   }
 
   for (char C : S)
-    BV[C] = true;
+    BV[(uint8_t)C] = true;
   return BV;
 }
 
@@ -89,7 +89,7 @@
   }
   default:
     BitVector BV(256, false);
-    BV[S[0]] = true;
+    BV[(uint8_t)S[0]] = true;
     S = S.substr(1);
     return BV;
   }
@@ -159,7 +159,7 @@
     }
 
     // If Pats[0] is not '*', it must consume one character.
-    if (S.empty() || !Pats[0][S[0]])
+    if (S.empty() || !Pats[0][(uint8_t)S[0]])
       return false;
     Pats = Pats.slice(1);
     S = S.substr(1);
Index: unittests/Support/GlobPatternTest.cpp
===================================================================
--- unittests/Support/GlobPatternTest.cpp
+++ unittests/Support/GlobPatternTest.cpp
@@ -67,4 +67,13 @@
   EXPECT_FALSE((bool)Pat1);
   handleAllErrors(Pat1.takeError(), [&](ErrorInfoBase &EIB) {});
 }
+
+TEST_F(GlobPatternTest, ExtSym) {
+  Expected<GlobPattern> Pat1 = GlobPattern::create("a*\xFF");
+  EXPECT_TRUE((bool)Pat1);
+  EXPECT_TRUE(Pat1->match("axxx\xFF"));
+  Expected<GlobPattern> Pat2 = GlobPattern::create("[\xFF-\xFF]");
+  EXPECT_TRUE((bool)Pat2);
+  EXPECT_TRUE(Pat2->match("\xFF"));
+}
 }