diff --git a/include/clang/Sema/DeclSpec.h b/include/clang/Sema/DeclSpec.h
index 6a180e8..c4a96e1 100644
--- a/include/clang/Sema/DeclSpec.h
+++ b/include/clang/Sema/DeclSpec.h
@@ -1747,7 +1747,6 @@
         return !DeclTypeInfo[i].Arr.NumElts;
       }
       llvm_unreachable("Invalid type chunk");
-      return false;
     }
     return false;
   }
@@ -1772,7 +1771,6 @@
         return false;
       }
       llvm_unreachable("Invalid type chunk");
-      return false;
     }
     return false;
   }
diff --git a/include/clang/Sema/Overload.h b/include/clang/Sema/Overload.h
index 24adce8..3fcc567 100644
--- a/include/clang/Sema/Overload.h
+++ b/include/clang/Sema/Overload.h
@@ -469,7 +469,7 @@
         return 3;
       }
 
-      return 3;
+      llvm_unreachable("Invalid ImplicitConversionSequence::Kind!");
     }
 
     bool isBad() const { return getKind() == BadConversion; }
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 24ccba1..8b0075f 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -4846,7 +4846,7 @@
 
       }
 
-      return true;
+      llvm_unreachable("Invalid InstantiationKind!");
     }
 
     friend bool operator!=(const ActiveTemplateInstantiation &X,
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index e145eec..9079dbe 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -193,7 +193,7 @@
   case CXXABI_Microsoft:
     return CreateMicrosoftCXXABI(*this);
   }
-  return 0;
+  llvm_unreachable("Invalid CXXABI type!");
 }
 
 static const LangAS::Map *getAddressSpaceMap(const TargetInfo &T,
@@ -833,7 +833,6 @@
 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
 #include "clang/AST/TypeNodes.def"
     llvm_unreachable("Should not see dependent types");
-    break;
 
   case Type::FunctionNoProto:
   case Type::FunctionProto:
@@ -3407,8 +3406,7 @@
     return NNS;
   }
 
-  // Required to silence a GCC warning
-  return 0;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 
@@ -6087,7 +6085,7 @@
                                           LHS->getAs<ObjCObjectPointerType>(),
                                           RHS->getAs<ObjCObjectPointerType>(),
                                           BlockReturnType))
-      return LHS;
+        return LHS;
       return QualType();
     }
     if (canAssignObjCInterfaces(LHS->getAs<ObjCObjectPointerType>(),
@@ -6095,10 +6093,10 @@
       return LHS;
 
     return QualType();
-    }
+  }
   }
 
-  return QualType();
+  llvm_unreachable("Invalid Type::Class!");
 }
 
 bool ASTContext::FunctionTypesMatchOnNSConsumedAttrs(
@@ -6613,7 +6611,7 @@
     }
   }
 
-  return GVA_StrongExternal;
+  llvm_unreachable("Invalid Linkage!");
 }
 
 bool ASTContext::DeclMustBeEmitted(const Decl *D) {
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index c191456..a76a363 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <cstdio>
 
 using namespace clang;
@@ -503,5 +504,5 @@
 #include "clang/Basic/OperatorKinds.def"
   }
 
-  return 0;
+  llvm_unreachable("Invalid OverloadedOperatorKind!");
 }
diff --git a/lib/Basic/Module.cpp b/lib/Basic/Module.cpp
index c5bc86d..ff09441 100644
--- a/lib/Basic/Module.cpp
+++ b/lib/Basic/Module.cpp
@@ -72,7 +72,6 @@
   }
 
   llvm_unreachable("could not find a reason why module is unavailable");
-  return false;
 }
 
 bool Module::isSubModuleOf(Module *Other) const {
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index b6c0756..9ba743c 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -2103,7 +2103,6 @@
             // x86_64 instructions.
     return true;
   }
-  return false;
 }
 
 
@@ -3397,7 +3396,6 @@
       Info.setAllowsRegister();
       return true;
     }
-    return false;
   }
 
   virtual const char *getClobbers() const {
diff --git a/lib/Lex/HeaderSearch.cpp b/lib/Lex/HeaderSearch.cpp
index 6d2d72f..7af7c93 100644
--- a/lib/Lex/HeaderSearch.cpp
+++ b/lib/Lex/HeaderSearch.cpp
@@ -799,8 +799,6 @@
     // having module maps if we eventually do find a module map.
     FixUpDirectories.push_back(Dir);
   } while (true);
-  
-  return false;
 }
 
 Module *HeaderSearch::findModuleForHeader(const FileEntry *File) {
diff --git a/lib/Lex/ModuleMap.cpp b/lib/Lex/ModuleMap.cpp
index 745ebc4..08a1e23 100644
--- a/lib/Lex/ModuleMap.cpp
+++ b/lib/Lex/ModuleMap.cpp
@@ -1263,8 +1263,6 @@
       break;
     }
   } while (true);
-  
-  return HadError;
 }
 
 bool ModuleMap::parseModuleMapFile(const FileEntry *File) {
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index 4379b6b..7695560 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -1370,7 +1370,6 @@
         
     default:
       llvm_unreachable("unknown include directive kind");
-      break;
     }
 
     // Determine whether we are actually building the module that this
diff --git a/lib/Lex/PPExpressions.cpp b/lib/Lex/PPExpressions.cpp
index 20f624a..4ce48e0 100644
--- a/lib/Lex/PPExpressions.cpp
+++ b/lib/Lex/PPExpressions.cpp
@@ -703,8 +703,6 @@
     LHS.Val = Res;
     LHS.setEnd(RHS.getRange().getEnd());
   }
-
-  return false;
 }
 
 /// EvaluateDirectiveExpression - Evaluate an integer constant expression that
diff --git a/lib/Lex/PreprocessingRecord.cpp b/lib/Lex/PreprocessingRecord.cpp
index 770a69d..6c36e73 100644
--- a/lib/Lex/PreprocessingRecord.cpp
+++ b/lib/Lex/PreprocessingRecord.cpp
@@ -390,7 +390,6 @@
     
   default:
     llvm_unreachable("Unknown include directive kind");
-    return;
   }
   
   clang::InclusionDirective *ID
diff --git a/lib/Lex/TokenConcatenation.cpp b/lib/Lex/TokenConcatenation.cpp
index dc6d686..335d864 100644
--- a/lib/Lex/TokenConcatenation.cpp
+++ b/lib/Lex/TokenConcatenation.cpp
@@ -179,11 +179,9 @@
   switch (PrevKind) {
   default:
     llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
-    return true;
 
   case tok::raw_identifier:
     llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
-    return true;
 
   case tok::identifier:   // id+id or id+number or id+L"foo".
     // id+'.'... will not append.
diff --git a/lib/Parse/ParseObjc.cpp b/lib/Parse/ParseObjc.cpp
index 3ecdae2..3f4f461 100644
--- a/lib/Parse/ParseObjc.cpp
+++ b/lib/Parse/ParseObjc.cpp
@@ -42,7 +42,6 @@
   switch (Tok.getObjCKeywordID()) {
   case tok::objc_class:
     return ParseObjCAtClassDeclaration(AtLoc);
-    break;
   case tok::objc_interface: {
     ParsedAttributes attrs(AttrFactory);
     SingleDecl = ParseObjCAtInterfaceDeclaration(AtLoc, attrs);
@@ -426,7 +425,6 @@
     if (Tok.is(tok::code_completion)) {
       Actions.CodeCompleteObjCAtDirective(getCurScope());
       return cutOffParsing();
-      break;
     }
 
     tok::ObjCKeywordKind DirectiveKind = Tok.getObjCKeywordID();
diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index fadf34f..cd467dd 100644
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -1934,8 +1934,6 @@
     if (Tok.isNot(tok::comma)) return false;
     ConsumeToken();
   }
-
-  return true;
 }
 
 Decl *Parser::ParseFunctionStatementBody(Decl *Decl, ParseScope &BodyScope) {
@@ -2203,7 +2201,6 @@
       
   case IEB_Dependent:
     llvm_unreachable("Dependent case handled above");
-    break;
       
   case IEB_Skip:
     Braces.skipToEnd();
diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index db9460b..501e50c 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -581,7 +581,6 @@
   }
   case tok::at:
     return ParseObjCAtDirectives();
-    break;
   case tok::minus:
   case tok::plus:
     if (!getLang().ObjC1) {
diff --git a/lib/Rewrite/HTMLRewrite.cpp b/lib/Rewrite/HTMLRewrite.cpp
index ba39602..ed4974b 100644
--- a/lib/Rewrite/HTMLRewrite.cpp
+++ b/lib/Rewrite/HTMLRewrite.cpp
@@ -381,7 +381,6 @@
     default: break;
     case tok::identifier:
       llvm_unreachable("tok::identifier in raw lexing mode!");
-      break;
     case tok::raw_identifier: {
       // Fill in Result.IdentifierInfo and update the token kind,
       // looking up the identifier in the identifier table.
diff --git a/lib/Sema/CodeCompleteConsumer.cpp b/lib/Sema/CodeCompleteConsumer.cpp
index 80496c5..f1a6392 100644
--- a/lib/Sema/CodeCompleteConsumer.cpp
+++ b/lib/Sema/CodeCompleteConsumer.cpp
@@ -71,8 +71,8 @@
   case CCC_ObjCCategoryName:
     return false;
   }
-  
-  return false;
+
+  llvm_unreachable("Invalid CodeCompletionContext::Kind!");
 }
 
 //===----------------------------------------------------------------------===//
@@ -93,7 +93,6 @@
 
   case CK_Optional:
     llvm_unreachable("Optional strings cannot be created from text");
-    break;
       
   case CK_LeftParen:
     this->Text = "(";
@@ -330,8 +329,8 @@
   case CK_FunctionType:
     return Type;
   }
-  
-  return 0;
+
+  llvm_unreachable("Invalid CandidateKind!");
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Sema/DeclSpec.cpp b/lib/Sema/DeclSpec.cpp
index 2b5efc6..11818f6 100644
--- a/lib/Sema/DeclSpec.cpp
+++ b/lib/Sema/DeclSpec.cpp
@@ -245,7 +245,6 @@
       return false;
     }
     llvm_unreachable("Invalid type chunk");
-    return false;
   }
   
   switch (DS.getTypeSpecType()) {
@@ -295,8 +294,8 @@
       return QT->isFunctionType();
     }
   }
-  
-  return false;
+
+  llvm_unreachable("Invalid TypeSpecType!");
 }
 
 /// getParsedSpecifiers - Return a bitmask of which flavors of specifiers this
diff --git a/lib/Sema/SemaAccess.cpp b/lib/Sema/SemaAccess.cpp
index e1322ed..6014b9b 100644
--- a/lib/Sema/SemaAccess.cpp
+++ b/lib/Sema/SemaAccess.cpp
@@ -797,7 +797,6 @@
 
   // Silence bogus warnings
   llvm_unreachable("impossible friendship kind");
-  return OnFailure;
 }
 
 /// Finds the best path from the naming class to the declaring class,
@@ -1068,7 +1067,6 @@
 
     case AR_dependent:
       llvm_unreachable("can't diagnose dependent access failures");
-      return;
     }
   }
 
@@ -1298,7 +1296,6 @@
 
   // silence unnecessary warning
   llvm_unreachable("invalid access result");
-  return AR_accessible;
 }
 
 static Sema::AccessResult CheckAccess(Sema &S, SourceLocation Loc,
@@ -1333,7 +1330,6 @@
   case AR_dependent: return Sema::AR_dependent;
   }
   llvm_unreachable("falling off end");
-  return Sema::AR_accessible;
 }
 
 void Sema::HandleDelayedAccessCheck(DelayedDiagnostic &DD, Decl *decl) {
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 31e33dd..1ad5043 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -150,14 +150,13 @@
     const TagType *Tag = NNS->getAsType()->getAs<TagType>();
     assert(Tag && "Non-tag type in nested-name-specifier");
     return Tag->getDecl();
-  } break;
+  }
 
   case NestedNameSpecifier::Global:
     return Context.getTranslationUnitDecl();
   }
 
-  // Required to silence a GCC warning.
-  return 0;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
@@ -899,8 +898,7 @@
     return true;
   }
 
-  // Silence bogus warning.
-  return false;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index fe7667e..2420424 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -295,8 +295,6 @@
                                                  OpLoc, Parens.getEnd()));
   }
   }
-
-  return ExprError();
 }
 
 /// Try to diagnose a failed overloaded cast.  Returns true if
@@ -346,7 +344,6 @@
 
   switch (sequence.getFailedOverloadResult()) {
   case OR_Success: llvm_unreachable("successful failed overload");
-    return false;
   case OR_No_Viable_Function:
     if (candidates.empty())
       msg = diag::err_ovl_no_conversion_in_cast;
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index af0eedd..e94aa2f 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -342,7 +342,7 @@
     assert(!shift && "cannot shift float types!");
     return (2 << IsQuad) - 1;
   }
-  return 0;
+  llvm_unreachable("Invalid NeonTypeFlag!");
 }
 
 /// getNeonEltType - Return the QualType corresponding to the elements of
@@ -367,7 +367,7 @@
   case NeonTypeFlags::Float32:
     return Context.FloatTy;
   }
-  return QualType();
+  llvm_unreachable("Invalid NeonTypeFlag!");
 }
 
 bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index c280ac2..730dde8 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -596,8 +596,7 @@
       default:
         return STC_Arithmetic;
     }
-    return STC_Other;
-    
+
   case Type::Complex:
     return STC_Arithmetic;
     
@@ -1370,8 +1369,8 @@
   case Sema::PCC_ForInit:
     return LangOpts.CPlusPlus || LangOpts.ObjC1 || LangOpts.C99;
   }
-  
-  return false;
+
+  llvm_unreachable("Invalid ParserCompletionContext!");
 }
 
 static PrintingPolicy getCompletionPrintingPolicy(const ASTContext &Context,
@@ -2793,7 +2792,7 @@
     case Decl::ObjCCategory:       return CXCursor_ObjCCategoryDecl;
     case Decl::ObjCCategoryImpl:   return CXCursor_ObjCCategoryImplDecl;
       // FIXME
-      return CXCursor_UnexposedDecl;
+      // return CXCursor_UnexposedDecl;
     case Decl::ObjCImplementation: return CXCursor_ObjCImplementationDecl;
 
     case Decl::ObjCInterface:
@@ -2847,7 +2846,6 @@
       case ObjCPropertyImplDecl::Synthesize:
         return CXCursor_ObjCSynthesizeDecl;
       }
-      break;
       
     default:
       if (TagDecl *TD = dyn_cast<TagDecl>(D)) {
@@ -2926,10 +2924,9 @@
   case Sema::PCC_MemberTemplate:
     if (S.CurContext->isFileContext())
       return CodeCompletionContext::CCC_TopLevel;
-    else if (S.CurContext->isRecord())
+    if (S.CurContext->isRecord())
       return CodeCompletionContext::CCC_ClassStructUnion;
-    else 
-      return CodeCompletionContext::CCC_Other;
+    return CodeCompletionContext::CCC_Other;
       
   case Sema::PCC_RecoveryInFunction:
     return CodeCompletionContext::CCC_Recovery;
@@ -2957,8 +2954,8 @@
   case Sema::PCC_LocalDeclarationSpecifiers:
     return CodeCompletionContext::CCC_Type;
   }
-  
-  return CodeCompletionContext::CCC_Other;
+
+  llvm_unreachable("Invalid ParserCompletionContext!");
 }
 
 /// \brief If we're in a C++ virtual member function, add completion results
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 43bdf3f..ea73632 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -1105,7 +1105,6 @@
     return false;
   }
   llvm_unreachable("unknown linkage kind!");
-  return false;
 }
 
 static void handleWeakRefAttr(Sema &S, Decl *D, const AttributeList &Attr) {
@@ -3007,7 +3006,6 @@
   }
   default:
     llvm_unreachable("unexpected attribute kind");
-    return;
   }
 }
 
@@ -3056,7 +3054,7 @@
     }
     // FALLS THROUGH
   }
-  default: llvm_unreachable("unexpected attribute kind"); return true;
+  default: llvm_unreachable("unexpected attribute kind");
   }
 
   return false;
@@ -3242,7 +3240,7 @@
   bool typeOK;
   bool cf;
   switch (Attr.getKind()) {
-  default: llvm_unreachable("invalid ownership attribute"); return;
+  default: llvm_unreachable("invalid ownership attribute");
   case AttributeList::AT_ns_returns_autoreleased:
   case AttributeList::AT_ns_returns_retained:
   case AttributeList::AT_ns_returns_not_retained:
diff --git a/lib/Sema/SemaExceptionSpec.cpp b/lib/Sema/SemaExceptionSpec.cpp
index 92af2d9..eb7be5d 100644
--- a/lib/Sema/SemaExceptionSpec.cpp
+++ b/lib/Sema/SemaExceptionSpec.cpp
@@ -611,10 +611,8 @@
       case AR_inaccessible: continue;
       case AR_dependent:
         llvm_unreachable("access check dependent for unprivileged context");
-        break;
       case AR_delayed:
         llvm_unreachable("access check delayed in non-declaration");
-        break;
       }
 
       Contained = true;
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 741ca9e..26ca3a9 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2392,13 +2392,11 @@
     case Decl::type:
 #include "clang/AST/DeclNodes.inc"
       llvm_unreachable("invalid value decl kind");
-      return ExprError();
 
     // These shouldn't make it here.
     case Decl::ObjCAtDefsField:
     case Decl::ObjCIvar:
       llvm_unreachable("forming non-member reference to ivar?");
-      return ExprError();
 
     // Enum constants are always r-values and never references.
     // Unresolved using declarations are dependent.
@@ -2519,7 +2517,6 @@
   }
 
   llvm_unreachable("unknown capture result");
-  return ExprError();
 }
 
 ExprResult Sema::ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind) {
@@ -4090,12 +4087,10 @@
     case Type::STK_ObjCObjectPointer:
       if (SrcKind == Type::STK_ObjCObjectPointer)
         return CK_BitCast;
-      else if (SrcKind == Type::STK_CPointer)
+      if (SrcKind == Type::STK_CPointer)
         return CK_CPointerToObjCPointerCast;
-      else {
-        maybeExtendBlockObject(*this, Src);
-        return CK_BlockPointerToObjCPointerCast;
-      }
+      maybeExtendBlockObject(*this, Src);
+      return CK_BlockPointerToObjCPointerCast;
     case Type::STK_Bool:
       return CK_PointerToBoolean;
     case Type::STK_Integral:
@@ -4106,7 +4101,7 @@
     case Type::STK_MemberPointer:
       llvm_unreachable("illegal cast from pointer");
     }
-    break;
+    llvm_unreachable("Should have returned before this");
 
   case Type::STK_Bool: // casting from bool is like casting from an integer
   case Type::STK_Integral:
@@ -4137,7 +4132,7 @@
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     }
-    break;
+    llvm_unreachable("Should have returned before this");
 
   case Type::STK_Floating:
     switch (DestTy->getScalarTypeKind()) {
@@ -4164,7 +4159,7 @@
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     }
-    break;
+    llvm_unreachable("Should have returned before this");
 
   case Type::STK_FloatingComplex:
     switch (DestTy->getScalarTypeKind()) {
@@ -4193,7 +4188,7 @@
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     }
-    break;
+    llvm_unreachable("Should have returned before this");
 
   case Type::STK_IntegralComplex:
     switch (DestTy->getScalarTypeKind()) {
@@ -4222,7 +4217,7 @@
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     }
-    break;
+    llvm_unreachable("Should have returned before this");
   }
 
   llvm_unreachable("Unhandled scalar cast");
@@ -7201,7 +7196,6 @@
   case Expr::MLV_ReadonlyProperty:
   case Expr::MLV_NoSetterProperty:
     llvm_unreachable("readonly properties should be processed differently");
-    break;
   case Expr::MLV_InvalidMessageExpression:
     Diag = diag::error_readonly_message_assignment;
     break;
@@ -9924,7 +9918,6 @@
 
     ExprResult VisitStmt(Stmt *S) {
       llvm_unreachable("unexpected statement!");
-      return ExprError();
     }
 
     ExprResult VisitExpr(Expr *E) {
@@ -10017,7 +10010,6 @@
 
     ExprResult VisitStmt(Stmt *S) {
       llvm_unreachable("unexpected statement!");
-      return ExprError();
     }
 
     ExprResult VisitExpr(Expr *E) {
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 6476f4a..fceb639 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -4786,8 +4786,8 @@
   case LookupResult::NotFoundInCurrentInstantiation:
     return IER_Dependent;
   }
-  
-  return IER_DoesNotExist;  
+
+  llvm_unreachable("Invalid LookupResult Kind!");
 }
 
 Sema::IfExistsResult 
diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
index 0080156..fb0fc34 100644
--- a/lib/Sema/SemaExprMember.cpp
+++ b/lib/Sema/SemaExprMember.cpp
@@ -238,7 +238,6 @@
   }
 
   llvm_unreachable("unexpected instance member access kind");
-  return ExprError();
 }
 
 /// Check an ext-vector component access expression.
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index cd85059..8a4f683 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -2327,8 +2327,7 @@
     return DeclarationName();
   }
 
-  // Silence GCC warning
-  return DeclarationName();
+  llvm_unreachable("Invalid EntityKind!");
 }
 
 DeclaratorDecl *InitializedEntity::getDecl() const {
@@ -2353,8 +2352,7 @@
     return 0;
   }
 
-  // Silence GCC warning
-  return 0;
+  llvm_unreachable("Invalid EntityKind!");
 }
 
 bool InitializedEntity::allowsNRVO() const {
@@ -2456,7 +2454,7 @@
     return FailedOverloadResult == OR_Ambiguous;
   }
 
-  return false;
+  llvm_unreachable("Invalid EntityKind!");
 }
 
 bool InitializationSequence::isConstructorInitialization() const {
@@ -4263,7 +4261,7 @@
     return Sema::AA_Initializing;
   }
 
-  return Sema::AA_Converting;
+  llvm_unreachable("Invalid EntityKind!");
 }
 
 /// \brief Whether we should binding a created object as a temporary when
@@ -5356,7 +5354,6 @@
 
     case OR_Success:
       llvm_unreachable("Conversion did not fail!");
-      break;
     }
     break;
 
@@ -5541,9 +5538,7 @@
 
       case OR_Success:
         llvm_unreachable("Conversion did not fail!");
-        break;
     }
-    break;
   }
 
   case FK_DefaultInitOfConst:
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 8281597..d14bf90 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -2762,7 +2762,8 @@
       User.After.setFromType(ThisType->getAs<PointerType>()->getPointeeType());
       User.After.setAllToTypes(ToType);
       return OR_Success;
-    } else if (CXXConversionDecl *Conversion
+    }
+    if (CXXConversionDecl *Conversion
                  = dyn_cast<CXXConversionDecl>(Best->Function)) {
       S.MarkDeclarationReferenced(From->getLocStart(), Conversion);
 
@@ -2789,10 +2790,8 @@
       //   13.3.3.1).
       User.After = Best->FinalConversion;
       return OR_Success;
-    } else {
-      llvm_unreachable("Not a constructor or conversion function?");
-      return OR_No_Viable_Function;
     }
+    llvm_unreachable("Not a constructor or conversion function?");
 
   case OR_No_Viable_Function:
     return OR_No_Viable_Function;
@@ -2804,7 +2803,7 @@
     return OR_Ambiguous;
   }
 
-  return OR_No_Viable_Function;
+  llvm_unreachable("Invalid OverloadResult!");
 }
 
 bool
@@ -2852,7 +2851,7 @@
   //   from any other user-defined conversion sequence.
   if (ICS1.getKindRank() < ICS2.getKindRank())
     return ImplicitConversionSequence::Better;
-  else if (ICS2.getKindRank() < ICS1.getKindRank())
+  if (ICS2.getKindRank() < ICS1.getKindRank())
     return ImplicitConversionSequence::Worse;
 
   // The following checks require both conversion sequences to be of
@@ -3664,7 +3663,7 @@
     return false;
   }
 
-  return false;
+  llvm_unreachable("Invalid OverloadResult!");
 }
 
 /// \brief Compute an implicit conversion sequence for reference
@@ -8993,7 +8992,6 @@
       return BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, NumArgs,
                                    RParenLoc, ExecConfig);
     }
-    break;
   }
 
   // Overload resolution failed.
@@ -10422,7 +10420,6 @@
   }
 
   llvm_unreachable("Invalid reference to overloaded function");
-  return E;
 }
 
 ExprResult Sema::FixOverloadedFunctionReference(ExprResult E,
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 35022be..f58e965 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -502,7 +502,6 @@
   }
 
   llvm_unreachable("Unhandled parsed template argument");
-  return TemplateArgumentLoc();
 }
 
 /// \brief Translates template arguments as provided by the parser
@@ -1139,7 +1138,7 @@
     // declaration (and it is a definition). Strange!
   }
 
-  return false;
+  llvm_unreachable("Invalid TemplateParamListContext!");
 }
 
 /// \brief Check for unexpanded parameter packs within the template parameters
@@ -2789,7 +2788,6 @@
 
     case TemplateArgument::Pack:
       llvm_unreachable("Caller must expand template argument packs");
-      break;
     }
 
     return false;
@@ -2839,17 +2837,12 @@
     return true;
 
   case TemplateArgument::Declaration:
-    llvm_unreachable(
-                       "Declaration argument with template template parameter");
-    break;
+    llvm_unreachable("Declaration argument with template template parameter");
   case TemplateArgument::Integral:
-    llvm_unreachable(
-                          "Integral argument with template template parameter");
-    break;
+    llvm_unreachable("Integral argument with template template parameter");
 
   case TemplateArgument::Pack:
     llvm_unreachable("Caller must expand template argument packs");
-    break;
   }
 
   return false;
@@ -3306,7 +3299,7 @@
   case NestedNameSpecifier::TypeSpecWithTemplate:
     return Visit(QualType(NNS->getAsType(), 0));
   }
-  return false;
+  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
 }
 
 
@@ -5324,7 +5317,6 @@
 
       return true;
     }
-    break;
 
   case TSK_ExplicitInstantiationDeclaration:
     switch (PrevTSK) {
@@ -5364,7 +5356,6 @@
       HasNoEffect = true;
       return false;
     }
-    break;
 
   case TSK_ExplicitInstantiationDefinition:
     switch (PrevTSK) {
@@ -5424,7 +5415,6 @@
       HasNoEffect = true;
       return false;
     }
-    break;
   }
 
   llvm_unreachable("Missing specialization/instantiation case?");
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 03376fa..a41878f 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -163,8 +163,8 @@
   case DefaultTemplateArgumentChecking:
     return false;
   }
-  
-  return true;
+
+  llvm_unreachable("Invalid InstantiationKind!");
 }
 
 Sema::InstantiatingTemplate::
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 7fc5a1d..ab6a251 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1398,10 +1398,8 @@
       Macro->AddTokenToBody(Tok);
       break;
     }
+    }
   }
-  }
-  
-  return;
 }
 
 PreprocessedEntityID 
@@ -3275,8 +3273,6 @@
     }
     }
   }
-
-  return Success;
 }
 
 /// \brief Parse the record that corresponds to a LangOptions data
@@ -3413,9 +3409,8 @@
     return ID;
   }
   }
-  
-  Error("invalid offset in preprocessor detail block");
-  return 0;
+
+  llvm_unreachable("Invalid PreprocessorDetailRecordTypes");
 }
 
 /// \brief \arg SLocMapI points at a chunk of a module that contains no
@@ -4101,8 +4096,7 @@
     return Context.getAtomicType(ValueType);
   }
   }
-  // Suppress a GCC warning
-  return QualType();
+  llvm_unreachable("Invalid TypeCode!");
 }
 
 class clang::TypeLocReader : public TypeLocVisitor<TypeLocReader> {
@@ -4483,7 +4477,6 @@
     return TemplateArgumentLocInfo();
   }
   llvm_unreachable("unexpected template argument loc");
-  return TemplateArgumentLocInfo();
 }
 
 TemplateArgumentLoc
@@ -4600,15 +4593,12 @@
     case PREDEF_DECL_OBJC_INSTANCETYPE_ID:
       return Context.getObjCInstanceTypeDecl();
     }
-    
-    return 0;
   }
   
   unsigned Index = ID - NUM_PREDEF_DECL_IDS;
 
   if (Index >= DeclsLoaded.size()) {
     Error("declaration ID out-of-range for AST file");
-    return 0;
   }
   
   if (!DeclsLoaded[Index]) {
@@ -5636,8 +5626,7 @@
     return DeclarationName::getUsingDirectiveName();
   }
 
-  // Required to silence GCC warning
-  return DeclarationName();
+  llvm_unreachable("Invalid NameKind!");
 }
 
 void ASTReader::ReadDeclarationNameLoc(ModuleFile &F,
diff --git a/lib/Serialization/ASTReaderStmt.cpp b/lib/Serialization/ASTReaderStmt.cpp
index bdb7cd5..a7dfa1b 100644
--- a/lib/Serialization/ASTReaderStmt.cpp
+++ b/lib/Serialization/ASTReaderStmt.cpp
@@ -1447,7 +1447,6 @@
   }
 
   llvm_unreachable("ReadingKind not set ?");
-  return 0;
 }
 
 Expr *ASTReader::ReadExpr(ModuleFile &F) {
@@ -1812,7 +1811,6 @@
       break;
     case EXPR_OBJC_KVC_REF_EXPR:
       llvm_unreachable("mismatching AST file");
-      break;
     case EXPR_OBJC_MESSAGE_EXPR:
       S = ObjCMessageExpr::CreateEmpty(Context,
                                      Record[ASTStmtReader::NumExprFields],
diff --git a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
index 59d0495..2f2f9d1 100644
--- a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -2732,7 +2732,7 @@
 
   switch (RE.getKind()) {
     default:
-      llvm_unreachable("Unhandled RetEffect."); break;
+      llvm_unreachable("Unhandled RetEffect.");
 
     case RetEffect::NoRet:
       // No work necessary.
@@ -2833,7 +2833,6 @@
     case IncRefMsg:
     case MakeCollectable:
       llvm_unreachable("DecRefMsg/IncRefMsg/MakeCollectable already converted");
-      return state;
 
     case Dealloc:
       // Any use of -dealloc in GC is *bad*.
@@ -2846,7 +2845,6 @@
       switch (V.getKind()) {
         default:
           llvm_unreachable("Invalid RefVal state for an explicit dealloc.");
-          break;
         case RefVal::Owned:
           // The object immediately transitions to the released state.
           V = V ^ RefVal::Released;
@@ -2890,7 +2888,6 @@
       switch (V.getKind()) {
         default:
           llvm_unreachable("Invalid RefVal state for a retain.");
-          break;
         case RefVal::Owned:
         case RefVal::NotOwned:
           V = V + 1;
@@ -2912,7 +2909,6 @@
         default:
           // case 'RefVal::Released' handled above.
           llvm_unreachable("Invalid RefVal state for a release.");
-          break;
 
         case RefVal::Owned:
           assert(V.getCount() > 0);
@@ -2956,7 +2952,6 @@
   switch (ErrorKind) {
     default:
       llvm_unreachable("Unhandled error.");
-      return;
     case RefVal::ErrorUseAfterRelease:
       if (!useAfterRelease)
         useAfterRelease.reset(new UseAfterRelease());
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 280a48c..db84ccd 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -181,7 +181,7 @@
     return VisitChildren(Cursor);
   }
 
-  return false;
+  llvm_unreachable("Invalid CXChildVisitResult!");
 }
 
 static bool visitPreprocessedEntitiesInRange(SourceRange R,
@@ -573,7 +573,6 @@
 
 bool CursorVisitor::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
   llvm_unreachable("Translation units are visited directly by Visit()");
-  return false;
 }
 
 bool CursorVisitor::VisitTypeAliasDecl(TypeAliasDecl *D) {
@@ -1134,8 +1133,8 @@
     // FIXME: Per-identifier location info?
     return false;
   }
-  
-  return false;
+
+  llvm_unreachable("Invalid DeclarationName::Kind!");
 }
 
 bool CursorVisitor::VisitNestedNameSpecifier(NestedNameSpecifier *NNS, 
@@ -1273,8 +1272,8 @@
                   Name.getAsSubstTemplateTemplateParmPack()->getParameterPack(),
                                        Loc, TU));
   }
-                 
-  return false;
+
+  llvm_unreachable("Invalid TemplateName::Kind!");
 }
 
 bool CursorVisitor::VisitTemplateArgumentLoc(const TemplateArgumentLoc &TAL) {
@@ -1307,8 +1306,8 @@
     return VisitTemplateName(TAL.getArgument().getAsTemplateOrTemplatePattern(), 
                              TAL.getTemplateNameLoc());
   }
-  
-  return false;
+
+  llvm_unreachable("Invalid TemplateArgument::Kind!");
 }
 
 bool CursorVisitor::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
@@ -3385,7 +3384,6 @@
   }
 
   llvm_unreachable("Unhandled CXCursorKind");
-  return createCXString((const char*) 0);
 }
 
 struct GetCursorData {
@@ -3962,11 +3960,8 @@
     default:
       // We would prefer to enumerate all non-reference cursor kinds here.
       llvm_unreachable("Unhandled reference cursor kind");
-      break;
     }
   }
-
-  return clang_getNullCursor();
 }
 
 CXCursor clang_getCursorDefinition(CXCursor C) {
diff --git a/tools/libclang/CIndexCXX.cpp b/tools/libclang/CIndexCXX.cpp
index fb0ccb1..240b0f6 100644
--- a/tools/libclang/CIndexCXX.cpp
+++ b/tools/libclang/CIndexCXX.cpp
@@ -46,9 +46,8 @@
     case AS_private: return CX_CXXPrivate;
     case AS_none: return CX_CXXInvalidAccessSpecifier;
   }
-  
-  // FIXME: Clang currently thinks this is reachable.
-  return CX_CXXInvalidAccessSpecifier;
+
+  llvm_unreachable("Invalid AccessSpecifier!");
 }
 
 enum CXCursorKind clang_getTemplateCursorKind(CXCursor C) {
diff --git a/tools/libclang/CIndexCodeCompletion.cpp b/tools/libclang/CIndexCodeCompletion.cpp
index c19b340..d8ac4cf 100644
--- a/tools/libclang/CIndexCodeCompletion.cpp
+++ b/tools/libclang/CIndexCodeCompletion.cpp
@@ -104,8 +104,7 @@
     return CXCompletionChunk_VerticalSpace;
   }
 
-  // Should be unreachable, but let's be careful.
-  return CXCompletionChunk_Text;
+  llvm_unreachable("Invalid CompletionKind!");
 }
 
 CXString clang_getCompletionChunkText(CXCompletionString completion_string,
@@ -182,8 +181,7 @@
     return (*CCStr)[chunk_number].Optional;
   }
 
-  // Should be unreachable, but let's be careful.
-  return 0;
+  llvm_unreachable("Invalid CompletionKind!");
 }
 
 unsigned clang_getNumCompletionChunks(CXCompletionString completion_string) {
diff --git a/tools/libclang/CIndexUSRs.cpp b/tools/libclang/CIndexUSRs.cpp
index 1c2ffbf..446baa0 100644
--- a/tools/libclang/CIndexUSRs.cpp
+++ b/tools/libclang/CIndexUSRs.cpp
@@ -395,7 +395,7 @@
       case TTK_Struct: Out << "@ST"; break;
       case TTK_Class:  Out << "@CT"; break;
       case TTK_Union:  Out << "@UT"; break;
-      case TTK_Enum: llvm_unreachable("enum template"); break;
+      case TTK_Enum: llvm_unreachable("enum template");
       }
       VisitTemplateParameterList(ClassTmpl->getTemplateParameters());
     } else if (ClassTemplatePartialSpecializationDecl *PartialSpec
@@ -406,7 +406,7 @@
       case TTK_Struct: Out << "@SP"; break;
       case TTK_Class:  Out << "@CP"; break;
       case TTK_Union:  Out << "@UP"; break;
-      case TTK_Enum: llvm_unreachable("enum partial specialization"); break;
+      case TTK_Enum: llvm_unreachable("enum partial specialization");
       }      
       VisitTemplateParameterList(PartialSpec->getTemplateParameters());
     }
diff --git a/tools/libclang/CXLoadedDiagnostic.cpp b/tools/libclang/CXLoadedDiagnostic.cpp
index b95515e..09049e8 100644
--- a/tools/libclang/CXLoadedDiagnostic.cpp
+++ b/tools/libclang/CXLoadedDiagnostic.cpp
@@ -84,7 +84,6 @@
   }
   
   llvm_unreachable("Invalid diagnostic level");
-  return CXDiagnostic_Ignored;
 }
 
 static CXSourceLocation makeLocation(const CXLoadedDiagnostic::Location *DLoc) {
@@ -297,7 +296,6 @@
         return 0;
       case Read_Record:
         llvm_unreachable("Top-level does not have records");
-        return 0;
       case Read_BlockEnd:
         continue;
       case Read_BlockBegin:
@@ -555,7 +553,6 @@
     switch (Res) {
       case Read_EndOfStream:
         llvm_unreachable("EndOfStream handled in readToNextRecordOrBlock");
-        return Failure;
       case Read_Failure:
         return Failure;
       case Read_BlockBegin: {
diff --git a/tools/libclang/CXStoredDiagnostic.cpp b/tools/libclang/CXStoredDiagnostic.cpp
index fb5d33d..c1bcd74 100644
--- a/tools/libclang/CXStoredDiagnostic.cpp
+++ b/tools/libclang/CXStoredDiagnostic.cpp
@@ -38,7 +38,6 @@
   }
   
   llvm_unreachable("Invalid diagnostic level");
-  return CXDiagnostic_Ignored;
 }
 
 CXSourceLocation CXStoredDiagnostic::getLocation() const {
diff --git a/utils/TableGen/NeonEmitter.cpp b/utils/TableGen/NeonEmitter.cpp
index 5d6dee6..e6f2e53 100644
--- a/utils/TableGen/NeonEmitter.cpp
+++ b/utils/TableGen/NeonEmitter.cpp
@@ -28,6 +28,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <string>
 
 using namespace llvm;
@@ -56,7 +57,6 @@
       default:
         throw TGError(r->getLoc(),
                       "Unexpected letter: " + std::string(data + len, 1));
-        break;
     }
     TV.push_back(StringRef(data, len + 1));
     data += len + 1;
@@ -78,7 +78,6 @@
       return 'f';
     default: throw "unhandled type in widen!";
   }
-  return '\0';
 }
 
 /// Narrow - Convert a type code into the next smaller type.  short -> char,
@@ -95,7 +94,6 @@
       return 'h';
     default: throw "unhandled type in narrow!";
   }
-  return '\0';
 }
 
 /// For a particular StringRef, return the base type code, and whether it has
@@ -266,7 +264,6 @@
       break;
     default:
       throw "unhandled type!";
-      break;
   }
 
   if (mod == '2')
@@ -449,7 +446,6 @@
     break;
   default:
     throw "unhandled type!";
-    break;
   }
   if (ck == ClassB)
     s += "_v";
@@ -588,7 +584,6 @@
   case 'f': nElts = 2; break;
   default:
     throw "unhandled type!";
-    break;
   }
   if (quad) nElts <<= 1;
   return nElts;
@@ -820,7 +815,6 @@
   }
   default:
     throw "unknown OpKind!";
-    break;
   }
   return s;
 }
@@ -866,7 +860,6 @@
       break;
     default:
       throw "unhandled type!";
-      break;
   }
   NeonTypeFlags Flags(ET, usgn, quad && proto[1] != 'g');
   return Flags.getFlags();
@@ -1239,10 +1232,7 @@
       return (1 << (int)quad) - 1;
     default:
       throw "unhandled type!";
-      break;
   }
-  assert(0 && "unreachable");
-  return 0;
 }
 
 /// runHeader - Emit a file with sections defining: