Index: lib/MC/MCParser/AsmLexer.cpp
===================================================================
--- lib/MC/MCParser/AsmLexer.cpp
+++ lib/MC/MCParser/AsmLexer.cpp
@@ -68,7 +68,7 @@
 /// consumed.
 AsmToken AsmLexer::LexFloatLiteral() {
   // Skip the fractional digit sequence.
-  while (isdigit(*CurPtr))
+  while (isdigit(static_cast<unsigned char>(*CurPtr)))
     ++CurPtr;
 
   // Check for exponent; we intentionally accept a slighlty wider set of
@@ -78,7 +78,7 @@
     ++CurPtr;
     if (*CurPtr == '-' || *CurPtr == '+')
       ++CurPtr;
-    while (isdigit(*CurPtr))
+    while (isdigit(static_cast<unsigned char>(*CurPtr)))
       ++CurPtr;
   }
 
@@ -102,7 +102,7 @@
     ++CurPtr;
 
     const char *FracStart = CurPtr;
-    while (isxdigit(*CurPtr))
+    while (isxdigit(static_cast<unsigned char>(*CurPtr)))
       ++CurPtr;
 
     NoFracDigits = CurPtr == FracStart;
@@ -123,7 +123,7 @@
 
   // N.b. exponent digits are *not* hex
   const char *ExpStart = CurPtr;
-  while (isdigit(*CurPtr))
+  while (isdigit(static_cast<unsigned char>(*CurPtr)))
     ++CurPtr;
 
   if (CurPtr == ExpStart)
@@ -135,15 +135,15 @@
 
 /// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@?]*
 static bool IsIdentifierChar(char c, bool AllowAt) {
-  return isalnum(c) || c == '_' || c == '$' || c == '.' ||
-         (c == '@' && AllowAt) || c == '?';
+  return isalnum(static_cast<unsigned char>(c)) || c == '_' || c == '$' ||
+         c == '.' || (c == '@' && AllowAt) || c == '?';
 }
 
 AsmToken AsmLexer::LexIdentifier() {
   // Check for floating point literals.
-  if (CurPtr[-1] == '.' && isdigit(*CurPtr)) {
+  if (CurPtr[-1] == '.' && isdigit(static_cast<unsigned char>(*CurPtr))) {
     // Disambiguate a .1243foo identifier from a floating literal.
-    while (isdigit(*CurPtr))
+    while (isdigit(static_cast<unsigned char>(*CurPtr)))
       ++CurPtr;
     if (*CurPtr == 'e' || *CurPtr == 'E' ||
         !IsIdentifierChar(*CurPtr, AllowAtInIdentifier))
@@ -244,9 +244,9 @@
   const char *FirstHex = nullptr;
   const char *LookAhead = CurPtr;
   while (true) {
-    if (isdigit(*LookAhead)) {
+    if (isdigit(static_cast<unsigned char>(*LookAhead))) {
       ++LookAhead;
-    } else if (isxdigit(*LookAhead)) {
+    } else if (isxdigit(static_cast<unsigned char>(*LookAhead))) {
       if (!FirstHex)
         FirstHex = LookAhead;
       ++LookAhead;
@@ -282,7 +282,7 @@
     const char *FirstNonBinary = (CurPtr[-1] != '0' && CurPtr[-1] != '1') ?
                                    CurPtr - 1 : nullptr;
     const char *OldCurPtr = CurPtr;
-    while (isxdigit(*CurPtr)) {
+    while (isxdigit(static_cast<unsigned char>(*CurPtr))) {
       if (*CurPtr != '0' && *CurPtr != '1' && !FirstNonBinary)
         FirstNonBinary = CurPtr;
       ++CurPtr;
@@ -346,7 +346,7 @@
   if (!IsParsingMSInlineAsm && ((*CurPtr == 'b') || (*CurPtr == 'B'))) {
     ++CurPtr;
     // See if we actually have "0b" as part of something like "jmp 0b\n"
-    if (!isdigit(CurPtr[0])) {
+    if (!isdigit(static_cast<unsigned char>(CurPtr[0]))) {
       --CurPtr;
       StringRef Result(TokStart, CurPtr - TokStart);
       return AsmToken(AsmToken::Integer, Result, 0);
@@ -375,7 +375,7 @@
   if ((*CurPtr == 'x') || (*CurPtr == 'X')) {
     ++CurPtr;
     const char *NumStart = CurPtr;
-    while (isxdigit(CurPtr[0]))
+    while (isxdigit(static_cast<unsigned char>(CurPtr[0])))
       ++CurPtr;
 
     // "0x.0p0" is valid, and "0x0p0" (but not "0xp0" for example, which will be
Index: test/MC/AsmParser/non-english-characters.s
===================================================================
--- test/MC/AsmParser/non-english-characters.s
+++ test/MC/AsmParser/non-english-characters.s
@@ -0,0 +1,11 @@
+# RUN: llvm-mc -triple i386-linux-gnu < %s > %t
+# 0bﾑ
+# 0xﾑ
+# .ﾑ4
+# .Xﾑ
+# .1ﾑ
+# .1eﾑ
+# 0x.ﾑ
+# 0x0pﾑ
+.intel_syntax
+# 1ﾑ