Index: lldb/trunk/include/lldb/Core/ArchSpec.h
===================================================================
--- lldb/trunk/include/lldb/Core/ArchSpec.h
+++ lldb/trunk/include/lldb/Core/ArchSpec.h
@@ -418,8 +418,18 @@
     GetDefaultEndian () const;
 
     //------------------------------------------------------------------
-    /// Compare an ArchSpec to another ArchSpec, requiring an exact cpu 
-    /// type match between them.  
+    /// Returns true if 'char' is a signed type by defualt in the 
+    /// architecture false otherwise
+    ///
+    /// @return True if 'char' is a signed type by default on the
+    ///         architecture and false otherwise.
+    //------------------------------------------------------------------
+    bool
+    CharIsSignedByDefault () const;
+
+    //------------------------------------------------------------------
+    /// Compare an ArchSpec to another ArchSpec, requiring an exact cpu
+    /// type match between them.
     /// e.g. armv7s is not an exact match with armv7 - this would return false
     ///
     /// @return true if the two ArchSpecs match.
Index: lldb/trunk/source/Core/ArchSpec.cpp
===================================================================
--- lldb/trunk/source/Core/ArchSpec.cpp
+++ lldb/trunk/source/Core/ArchSpec.cpp
@@ -577,6 +577,32 @@
     return eByteOrderInvalid;
 }
 
+bool
+ArchSpec::CharIsSignedByDefault () const
+{
+    switch (m_triple.getArch()) {
+    default:
+        return true;
+
+    case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_be:
+    case llvm::Triple::arm:
+    case llvm::Triple::armeb:
+    case llvm::Triple::thumb:
+    case llvm::Triple::thumbeb:
+        return m_triple.isOSDarwin() || m_triple.isOSWindows();
+
+    case llvm::Triple::ppc:
+    case llvm::Triple::ppc64:
+        return m_triple.isOSDarwin();
+
+    case llvm::Triple::ppc64le:
+    case llvm::Triple::systemz:
+    case llvm::Triple::xcore:
+        return false;
+    }
+}
+
 lldb::ByteOrder
 ArchSpec::GetByteOrder () const
 {
Index: lldb/trunk/source/Expression/ClangExpressionParser.cpp
===================================================================
--- lldb/trunk/source/Expression/ClangExpressionParser.cpp
+++ lldb/trunk/source/Expression/ClangExpressionParser.cpp
@@ -228,6 +228,9 @@
     if (expr.DesiredResultType() == ClangExpression::eResultTypeId)
         m_compiler->getLangOpts().DebuggerCastResultToId = true;
 
+    m_compiler->getLangOpts().CharIsSigned =
+            ArchSpec(m_compiler->getTargetOpts().Triple.c_str()).CharIsSignedByDefault();
+
     // Spell checking is a nice feature, but it ends up completing a
     // lot of types that we didn't strictly speaking need to complete.
     // As a result, we spend a long time parsing and importing debug
Index: lldb/trunk/source/Symbol/ClangASTContext.cpp
===================================================================
--- lldb/trunk/source/Symbol/ClangASTContext.cpp
+++ lldb/trunk/source/Symbol/ClangASTContext.cpp
@@ -109,13 +109,8 @@
     return AS_none;
 }
 
-
 static void
-ParseLangArgs
-(
-    LangOptions &Opts,
-    InputKind IK
-)
+ParseLangArgs (LangOptions &Opts, InputKind IK, const char* triple)
 {
     // FIXME: Cleanup per-file based stuff.
 
@@ -235,7 +230,7 @@
 //    Opts.Exceptions = Args.hasArg(OPT_fexceptions);
 //    Opts.RTTI = !Args.hasArg(OPT_fno_rtti);
 //    Opts.Blocks = Args.hasArg(OPT_fblocks);
-//    Opts.CharIsSigned = !Args.hasArg(OPT_fno_signed_char);
+      Opts.CharIsSigned = ArchSpec(triple).CharIsSignedByDefault();
 //    Opts.ShortWChar = Args.hasArg(OPT_fshort_wchar);
 //    Opts.Freestanding = Args.hasArg(OPT_ffreestanding);
 //    Opts.NoBuiltin = Args.hasArg(OPT_fno_builtin) || Opts.Freestanding;
@@ -450,7 +445,7 @@
     if (m_language_options_ap.get() == nullptr)
     {
         m_language_options_ap.reset(new LangOptions());
-        ParseLangArgs(*m_language_options_ap, IK_ObjCXX);
+        ParseLangArgs(*m_language_options_ap, IK_ObjCXX, GetTargetTriple());
 //        InitializeLangOptions(*m_language_options_ap, IK_ObjCXX);
     }
     return m_language_options_ap.get();
@@ -952,18 +947,13 @@
                 if (QualTypeMatchesBitSize (bit_size, ast, ast->Int128Ty))
                     return ClangASTType (ast, ast->Int128Ty.getAsOpaquePtr());
                 break;
-                
+
             case DW_ATE_signed_char:
-                if (type_name)
+                if (ast->getLangOpts().CharIsSigned && type_name && streq(type_name, "char"))
                 {
-                    if (streq(type_name, "signed char"))
-                    {
-                        if (QualTypeMatchesBitSize (bit_size, ast, ast->SignedCharTy))
-                            return ClangASTType (ast, ast->SignedCharTy.getAsOpaquePtr());
-                    }
+                    if (QualTypeMatchesBitSize (bit_size, ast, ast->CharTy))
+                        return ClangASTType (ast, ast->CharTy.getAsOpaquePtr());
                 }
-                if (QualTypeMatchesBitSize (bit_size, ast, ast->CharTy))
-                    return ClangASTType (ast, ast->CharTy.getAsOpaquePtr());
                 if (QualTypeMatchesBitSize (bit_size, ast, ast->SignedCharTy))
                     return ClangASTType (ast, ast->SignedCharTy.getAsOpaquePtr());
                 break;
@@ -1013,8 +1003,13 @@
                 if (QualTypeMatchesBitSize (bit_size, ast, ast->UnsignedInt128Ty))
                     return ClangASTType (ast, ast->UnsignedInt128Ty.getAsOpaquePtr());
                 break;
-                
+
             case DW_ATE_unsigned_char:
+                if (!ast->getLangOpts().CharIsSigned && type_name && streq(type_name, "char"))
+                {
+                    if (QualTypeMatchesBitSize (bit_size, ast, ast->CharTy))
+                        return ClangASTType (ast, ast->CharTy.getAsOpaquePtr());
+                }
                 if (QualTypeMatchesBitSize (bit_size, ast, ast->UnsignedCharTy))
                     return ClangASTType (ast, ast->UnsignedCharTy.getAsOpaquePtr());
                 if (QualTypeMatchesBitSize (bit_size, ast, ast->UnsignedShortTy))