diff --git a/utils/TableGen/ClangDiagnosticsEmitter.cpp b/utils/TableGen/ClangDiagnosticsEmitter.cpp
index 1588f0b..d0ca5a1 100644
--- a/utils/TableGen/ClangDiagnosticsEmitter.cpp
+++ b/utils/TableGen/ClangDiagnosticsEmitter.cpp
@@ -24,42 +24,10 @@
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
-// Generic routines for all Clang TableGen backends.
-//===----------------------------------------------------------------------===//
-
-typedef std::vector<Record*> RecordVector;
-
-static const RecordVal* findRecordVal(const Record& R, const std::string &key) {  
-  typedef std::vector<RecordVal> RecordValVector;
-  const RecordValVector &Vals = R.getValues();
-  for (RecordValVector::const_iterator I=Vals.begin(), E=Vals.end(); I!=E; ++I)
-    if ((*I).getName() == key)
-      return &*I;
-  
-  return 0;
-}
-
-//===----------------------------------------------------------------------===//
 // Warning Tables (.inc file) generation.
 //===----------------------------------------------------------------------===//
 
-static void ProcessDiag(std::ostream &OS, const Record *DiagClass,
-                        const Record &R) {
-  OS << "DIAG(" << R.getName() << ", ";
-  OS << R.getValueAsDef("Class")->getName();
-  OS << ", diag::" << R.getValueAsDef("DefaultMapping")->getName();
-  OS << ", \"";
-  std::string S = R.getValueAsString("Text");
-  EscapeString(S);
-  OS << S << "\")\n";
-}
-
 void ClangDiagsDefsEmitter::run(std::ostream &OS) {
-  const RecordVector &Diags = Records.getAllDerivedDefinitions("Diagnostic");
-  
-  const Record* DiagClass = Records.getClass("Diagnostic");
-  assert(DiagClass && "No Diagnostic class defined.");  
-  
   // Write the #if guard
   if (!Component.empty()) {
     std::string ComponentName = UppercaseString(Component);
@@ -69,127 +37,73 @@
     OS << "#undef " << ComponentName << "START\n";
     OS << "#endif\n";
   }
+
+  const std::vector<Record*> &Diags =
+    Records.getAllDerivedDefinitions("Diagnostic");
   
-  for (RecordVector::const_iterator I=Diags.begin(), E=Diags.end(); I!=E; ++I) {
-    const Record &R = **I;
+  for (unsigned i = 0, e = Diags.size(); i != e; ++i) {
+    const Record &R = *Diags[i];
     // Filter by component.
     if (!Component.empty() && Component != R.getValueAsString("Component"))
       continue;
     
-    ProcessDiag(OS, DiagClass, R);
+    OS << "DIAG(" << R.getName() << ", ";
+    OS << R.getValueAsDef("Class")->getName();
+    OS << ", diag::" << R.getValueAsDef("DefaultMapping")->getName();
+    OS << ", \"";
+    std::string S = R.getValueAsString("Text");
+    EscapeString(S);
+    OS << S << "\")\n";
   }
 }
 
 //===----------------------------------------------------------------------===//
-// Warning Group Tables generation.
+// Warning Group Tables generation
 //===----------------------------------------------------------------------===//
 
-static const std::string &getOptName(const Record *R) {
-  const RecordVal *V = findRecordVal(*R, "Name");
-  assert(V && "Options must have a 'Name' value.");
-  const StringInit* SV = dynamic_cast<const StringInit*>(V->getValue());
-  assert(SV && "'Name' entry must be a string.");
-  return SV->getValue();
-}  
-
-namespace {
-struct VISIBILITY_HIDDEN CompareOptName {  
-  bool operator()(const Record* A, const Record* B) const {
-    return getOptName(A) < getOptName(B);
-  }
-};
-}
-
-typedef std::set<const Record*> DiagnosticSet;
-typedef std::map<const Record*, DiagnosticSet, CompareOptName> OptionMap;
-typedef llvm::DenseSet<const ListInit*> VisitedLists;
-
-static void BuildGroup(DiagnosticSet& DS, VisitedLists &Visited, const Init* X);
-
-static void BuildGroup(DiagnosticSet &DS, VisitedLists &Visited,
-                       const ListInit* LV) {
-
-  // Simple hack to prevent including a list multiple times.  This may be useful
-  // if one declares an Option by including a bunch of other Options that
-  // include other Options, etc.
-  if (Visited.count(LV))
-    return;
-  
-  Visited.insert(LV);
-  
-  // Iterate through the list and grab all DiagnosticControlled.
-  for (ListInit::const_iterator I = LV->begin(), E = LV->end(); I!=E; ++I)
-    BuildGroup(DS, Visited, *I);
-}
-
-static void BuildGroup(DiagnosticSet& DS, VisitedLists &Visited,
-                       const Record *Def) {
-
-  // If an Option includes another Option, inline the Diagnostics of the
-  // included Option.
-  if (Def->isSubClassOf("Option")) {
-    if (const RecordVal *V = findRecordVal(*Def, "Members"))
-      if (const ListInit *LV = dynamic_cast<const ListInit*>(V->getValue()))
-        BuildGroup(DS, Visited, LV);
-
-    return;
-  }
-  
-  if (Def->isSubClassOf("DiagnosticControlled"))
-    DS.insert(Def);
-}
-
-static void BuildGroup(DiagnosticSet& DS, VisitedLists &Visited,
-                       const Init* X) {
-
-  if (const DefInit *D = dynamic_cast<const DefInit*>(X))
-    BuildGroup(DS, Visited, D->getDef());
-  
-  // We may have some other cases here in the future.
-}
-
-
 void ClangDiagGroupsEmitter::run(std::ostream &OS) {
-  // Build up a map from options to controlled diagnostics.
-  OptionMap OM;
+  // Invert the 1-[0/1] mapping of diags to group into a one to many mapping of
+  // groups to diags in the group.
+  std::map<std::string, std::vector<const Record*> > DiagsInGroup;
   
-  const RecordVector &Opts = Records.getAllDerivedDefinitions("Option");
-  for (RecordVector::const_iterator I=Opts.begin(), E=Opts.end(); I != E; ++I)
-    if (const RecordVal* V = findRecordVal(**I, "Members"))
-      if (const ListInit* LV = dynamic_cast<const ListInit*>(V->getValue())) {        
-        VisitedLists Visited;
-        BuildGroup(OM[*I], Visited, LV);
-      }
+  const std::vector<Record*> &Diags =
+    Records.getAllDerivedDefinitions("Diagnostic");
   
-  // Iterate through the OptionMap and emit the declarations.
-  for (OptionMap::iterator I = OM.begin(), E = OM.end(); I!=E; ++I) {    
-    // Output the option.
-    OS << "static const diag::kind " << I->first->getName() << "[] = { ";
-    
-    DiagnosticSet &DS = I->second;
-    bool first = true;
-    for (DiagnosticSet::iterator I2 = DS.begin(), E2 = DS.end(); I2!=E2; ++I2) {
-      if (first)
-        first = false;
-      else
-        OS << ", ";
-        
-      OS << "diag::" << (*I2)->getName();
-    }
-    OS << " };\n";
+  for (unsigned i = 0, e = Diags.size(); i != e; ++i) {
+    const Record *R = Diags[i];
+    DefInit *DI = dynamic_cast<DefInit*>(R->getValueInit("Group"));
+    if (DI == 0) continue;
+    DiagsInGroup[DI->getDef()->getValueAsString("GroupName")].push_back(R);
   }
+  
+  // Walk through the groups emitting an array for each diagnostic of the diags
+  // that are mapped to.
+  OS << "\n#ifdef GET_DIAG_ARRAYS\n";
+  unsigned IDNo = 0;
+  unsigned MaxLen = 0;
+  for (std::map<std::string, std::vector<const Record*> >::iterator
+       I = DiagsInGroup.begin(), E = DiagsInGroup.end(); I != E; ++I) {
+    MaxLen = std::max(MaxLen, (unsigned)I->first.size());
     
-  // Now emit the OptionTable table.
-  OS << "\nstatic const WarningOption OptionTable[] = {";
-  bool first = true;
-  for (OptionMap::iterator I = OM.begin(), E = OM.end(); I!=E; ++I) {
-    if (first)
-      first = false;
-    else
-      OS << ',';
-    
-    OS << "\n  {\"" << getOptName(I->first)
-       << "\", DIAGS(" << I->first->getName() << ")}";
+    OS << "static const short DiagArray" << IDNo++
+       << "[] = { ";
+    std::vector<const Record*> &V = I->second;
+    for (unsigned i = 0, e = V.size(); i != e; ++i)
+      OS << "diag::" << V[i]->getName() << ", ";
+    OS << "-1 };\n";
   }
-  OS << "\n};\n";
+  OS << "#endif // GET_DIAG_ARRAYS\n\n";
+  
+  // Emit the table now.
+  OS << "\n#ifdef GET_DIAG_TABLE\n";
+  IDNo = 0;
+  for (std::map<std::string, std::vector<const Record*> >::iterator
+       I = DiagsInGroup.begin(), E = DiagsInGroup.end(); I != E; ++I) {
+    std::string S = I->first;
+    EscapeString(S);
+    OS << "  { \"" << S << "\","
+       << std::string(MaxLen-I->first.size()+1, ' ')
+       << "DiagArray" << IDNo++ << " },\n";
+  }
+  OS << "#endif // GET_DIAG_TABLE\n\n";
 }