diff --git a/include/llvm/CodeGen/MachineCodeEmitter.h b/include/llvm/CodeGen/MachineCodeEmitter.h
index 9876615..ece416c 100644
--- a/include/llvm/CodeGen/MachineCodeEmitter.h
+++ b/include/llvm/CodeGen/MachineCodeEmitter.h
@@ -18,8 +18,6 @@
 #define LLVM_CODEGEN_MACHINECODEEMITTER_H
 
 #include "llvm/Support/DataTypes.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
 
diff --git a/include/llvm/CodeGen/SelectionDAGISel.h b/include/llvm/CodeGen/SelectionDAGISel.h
index b98636a..d2c0dc4 100644
--- a/include/llvm/CodeGen/SelectionDAGISel.h
+++ b/include/llvm/CodeGen/SelectionDAGISel.h
@@ -19,8 +19,6 @@
 #include "llvm/Pass.h"
 #include "llvm/Constant.h"
 #include "llvm/CodeGen/SelectionDAG.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
   class FastISel;
diff --git a/include/llvm/Support/ErrorHandling.h b/include/llvm/Support/ErrorHandling.h
index 758d924..c7e4297 100644
--- a/include/llvm/Support/ErrorHandling.h
+++ b/include/llvm/Support/ErrorHandling.h
@@ -49,7 +49,11 @@
   void llvm_unreachable(void) NORETURN;
 }
 
-#define LLVM_UNREACHABLE(msg) do { assert(0 && msg); llvm_unreachable(); } while(0)
+#ifndef NDEBUG
+#define LLVM_UNREACHABLE(msg) do {cerr<<msg<<"\n";llvm_unreachable();}while(0)
+#else
+#define LLVM_UNREACHABLE(msg) llvm_unreachable()
+#endif
 
 #endif
 
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index e51699b..2bf7e51 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetFrameInfo.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
diff --git a/lib/Target/ARM/ARMCodeEmitter.cpp b/lib/Target/ARM/ARMCodeEmitter.cpp
index f436e97..d43a76e 100644
--- a/lib/Target/ARM/ARMCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMCodeEmitter.cpp
@@ -257,10 +257,10 @@
   else if (MO.isMBB())
     emitMachineBasicBlock(MO.getMBB(), ARM::reloc_arm_branch);
   else {
-    std::string msg;
-    raw_string_ostream Msg(msg);
-    Msg << "ERROR: Unknown type of MachineOperand: " << MO;
-    llvm_report_error(Msg.str());
+#ifndef NDEBUG
+    cerr << MO;
+#endif
+    llvm_unreachable();
   }
   return 0;
 }
@@ -588,7 +588,7 @@
   unsigned Opcode = MI.getDesc().Opcode;
   switch (Opcode) {
   default:
-    llvm_report_error("ARMCodeEmitter::emitPseudoInstruction");//FIXME:
+    LLVM_UNREACHABLE("ARMCodeEmitter::emitPseudoInstruction");//FIXME:
   case TargetInstrInfo::INLINEASM: {
     // We allow inline assembler nodes with empty bodies - they can
     // implicitly define registers, which is ok for JIT.
@@ -1119,8 +1119,9 @@
 void Emitter<CodeEmitter>::emitBranchInstruction(const MachineInstr &MI) {
   const TargetInstrDesc &TID = MI.getDesc();
 
-  if (TID.Opcode == ARM::TPsoft)
-    llvm_report_error("ARM::TPsoft FIXME"); // FIXME
+  if (TID.Opcode == ARM::TPsoft) {
+    LLVM_UNREACHABLE("ARM::TPsoft FIXME"); // FIXME
+  }
 
   // Part of binary is determined by TableGn.
   unsigned Binary = getBinaryCodeForInstr(MI);
diff --git a/lib/Target/ARM/ARMISelDAGToDAG.cpp b/lib/Target/ARM/ARMISelDAGToDAG.cpp
index 6d7e41c..71a6305 100644
--- a/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -30,6 +30,9 @@
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+
 using namespace llvm;
 
 static const unsigned arm_dsubreg_0 = 5;
diff --git a/lib/Target/ARM/ARMJITInfo.cpp b/lib/Target/ARM/ARMJITInfo.cpp
index bc28919..c9e04c9 100644
--- a/lib/Target/ARM/ARMJITInfo.cpp
+++ b/lib/Target/ARM/ARMJITInfo.cpp
@@ -123,12 +123,12 @@
   //   ldr pc, [pc,#-4]
   //   <addr>
   if (!sys::Memory::setRangeWritable((void*)StubAddr, 8)) {
-    llvm_report_error("ERROR: Unable to mark stub writable");
+    LLVM_UNREACHABLE("ERROR: Unable to mark stub writable");
   }
   *(intptr_t *)StubAddr = 0xe51ff004;  // ldr pc, [pc, #-4]
   *(intptr_t *)(StubAddr+4) = NewVal;
   if (!sys::Memory::setRangeExecutable((void*)StubAddr, 8)) {
-    llvm_report_error("ERROR: Unable to mark stub executable");
+    LLVM_UNREACHABLE("ERROR: Unable to mark stub executable");
   }
 }
 
diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index d9e21b8..67c4258 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -120,7 +120,7 @@
   case ARM::FSTD:
     NumFSTMGened++;
     return ARM::FSTMD;
-  default: llvm_report_error("Unhandled opcode!");
+  default: LLVM_UNREACHABLE("Unhandled opcode!");
   }
   return 0;
 }
@@ -442,7 +442,7 @@
   case ARM::FLDD: return ARM::FLDMD;
   case ARM::FSTS: return ARM::FSTMS;
   case ARM::FSTD: return ARM::FSTMD;
-  default: llvm_report_error("Unhandled opcode!");
+  default: LLVM_UNREACHABLE("Unhandled opcode!");
   }
   return 0;
 }
@@ -455,7 +455,7 @@
   case ARM::FLDD: return ARM::FLDMD;
   case ARM::FSTS: return ARM::FSTMS;
   case ARM::FSTD: return ARM::FSTMD;
-  default: llvm_report_error("Unhandled opcode!");
+  default: LLVM_UNREACHABLE("Unhandled opcode!");
   }
   return 0;
 }
diff --git a/lib/Target/ARM/Thumb1RegisterInfo.cpp b/lib/Target/ARM/Thumb1RegisterInfo.cpp
index 316f5ad..125b461 100644
--- a/lib/Target/ARM/Thumb1RegisterInfo.cpp
+++ b/lib/Target/ARM/Thumb1RegisterInfo.cpp
@@ -32,6 +32,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 static cl::opt<bool>
diff --git a/lib/Target/ARM/Thumb2RegisterInfo.cpp b/lib/Target/ARM/Thumb2RegisterInfo.cpp
index bca205a..f5a8b82 100644
--- a/lib/Target/ARM/Thumb2RegisterInfo.cpp
+++ b/lib/Target/ARM/Thumb2RegisterInfo.cpp
@@ -455,8 +455,7 @@
       break;
     }
     default:
-      llvm_report_error("Unsupported addressing mode!");
-      break;
+      LLVM_UNREACHABLE("Unsupported addressing mode!");
     }
 
     Offset += InstrOffs * Scale;
diff --git a/lib/Target/Alpha/AlphaCodeEmitter.cpp b/lib/Target/Alpha/AlphaCodeEmitter.cpp
index 56f515e..9a7c5a4 100644
--- a/lib/Target/Alpha/AlphaCodeEmitter.cpp
+++ b/lib/Target/Alpha/AlphaCodeEmitter.cpp
@@ -235,10 +235,10 @@
     MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(),
                                                Alpha::reloc_bsr, MO.getMBB()));
   } else {
-    std::string msg;
-    raw_string_ostream Msg(msg);
-    Msg << "ERROR: Unknown type of MachineOperand: " << MO;
-    llvm_report_error(Msg.str());
+#ifndef NDEBUG
+    cerr << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
+#endif
+    llvm_unreachable();
   }
 
   return rv;
diff --git a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
index a774850..6fa05fc 100644
--- a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
+++ b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
@@ -28,7 +28,9 @@
 #include "llvm/Intrinsics.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 using namespace llvm;
 
diff --git a/lib/Target/Alpha/AlphaISelLowering.cpp b/lib/Target/Alpha/AlphaISelLowering.cpp
index 176255c..49fb262 100644
--- a/lib/Target/Alpha/AlphaISelLowering.cpp
+++ b/lib/Target/Alpha/AlphaISelLowering.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Intrinsics.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 /// AddLiveIn - This helper function adds the specified physical register to the
diff --git a/lib/Target/Alpha/AlphaInstrInfo.cpp b/lib/Target/Alpha/AlphaInstrInfo.cpp
index 17a9bc2..62b5d4c 100644
--- a/lib/Target/Alpha/AlphaInstrInfo.cpp
+++ b/lib/Target/Alpha/AlphaInstrInfo.cpp
@@ -201,7 +201,7 @@
       .addReg(SrcReg, getKillRegState(isKill))
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else
-    llvm_report_error("Unhandled register class");
+    LLVM_UNREACHABLE("Unhandled register class");
 }
 
 void AlphaInstrInfo::storeRegToAddr(MachineFunction &MF, unsigned SrcReg,
@@ -217,7 +217,7 @@
   else if (RC == Alpha::GPRCRegisterClass)
     Opc = Alpha::STQ;
   else
-    llvm_report_error("Unhandled register class");
+    LLVM_UNREACHABLE("Unhandled register class");
   DebugLoc DL = DebugLoc::getUnknownLoc();
   MachineInstrBuilder MIB = 
     BuildMI(MF, DL, get(Opc)).addReg(SrcReg, getKillRegState(isKill));
@@ -246,7 +246,7 @@
     BuildMI(MBB, MI, DL, get(Alpha::LDQ), DestReg)
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else
-    llvm_report_error("Unhandled register class");
+    LLVM_UNREACHABLE("Unhandled register class");
 }
 
 void AlphaInstrInfo::loadRegFromAddr(MachineFunction &MF, unsigned DestReg,
@@ -261,7 +261,7 @@
   else if (RC == Alpha::GPRCRegisterClass)
     Opc = Alpha::LDQ;
   else
-    llvm_report_error("Unhandled register class");
+    LLVM_UNREACHABLE("Unhandled register class");
   DebugLoc DL = DebugLoc::getUnknownLoc();
   MachineInstrBuilder MIB = 
     BuildMI(MF, DL, get(Opc), DestReg);
diff --git a/lib/Target/Alpha/AlphaJITInfo.cpp b/lib/Target/Alpha/AlphaJITInfo.cpp
index 6e9579a..c62ab75 100644
--- a/lib/Target/Alpha/AlphaJITInfo.cpp
+++ b/lib/Target/Alpha/AlphaJITInfo.cpp
@@ -18,6 +18,7 @@
 #include "llvm/CodeGen/JITCodeEmitter.h"
 #include "llvm/Config/alloca.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <cstdlib>
 using namespace llvm;
 
diff --git a/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp b/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
index feab490..11f177d 100644
--- a/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
+++ b/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
@@ -101,7 +101,7 @@
     return;
 
   case MachineOperand::MO_Immediate:
-    llvm_report_error("printOp() does not handle immediate values");
+    LLVM_UNREACHABLE("printOp() does not handle immediate values");
     return;
 
   case MachineOperand::MO_MachineBasicBlock:
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 294c6d3..70495d0 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Target/TargetData.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/CFG.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
 #include "llvm/Support/InstVisitor.h"
 #include "llvm/Support/Mangler.h"
@@ -321,8 +322,10 @@
     void visitExtractValueInst(ExtractValueInst &I);
 
     void visitInstruction(Instruction &I) {
+#ifndef NDEBUG
       cerr << "C Writer does not know about " << I;
-      abort();
+#endif
+      llvm_unreachable();
     }
 
     void outputLValue(Instruction *I) {
@@ -505,8 +508,10 @@
   }
     
   default:
+#ifndef NDEBUG
     cerr << "Unknown primitive type: " << *Ty << "\n";
-    abort();
+#endif
+    llvm_unreachable();
   }
 }
 
@@ -550,8 +555,10 @@
   }
     
   default:
+#ifndef NDEBUG
     cerr << "Unknown primitive type: " << *Ty << "\n";
-    abort();
+#endif
+    llvm_unreachable();
   }
 }
 
@@ -652,8 +659,7 @@
     return Out << TyName << ' ' << NameSoFar;
   }
   default:
-    assert(0 && "Unhandled case in getTypeProps!");
-    abort();
+    LLVM_UNREACHABLE("Unhandled case in getTypeProps!");
   }
 
   return Out;
@@ -756,8 +762,7 @@
     return Out << TyName << ' ' << NameSoFar;
   }
   default:
-    assert(0 && "Unhandled case in getTypeProps!");
-    abort();
+    LLVM_UNREACHABLE("Unhandled case in getTypeProps!");
   }
 
   return Out;
@@ -1104,9 +1109,11 @@
       return;
     }
     default:
+#ifndef NDEBUG
       cerr << "CWriter Error: Unhandled constant expression: "
            << *CE << "\n";
-      abort();
+#endif
+      llvm_unreachable();
     }
   } else if (isa<UndefValue>(CPV) && CPV->getType()->isSingleValueType()) {
     Out << "((";
@@ -1312,8 +1319,10 @@
     }
     // FALL THROUGH
   default:
+#ifndef NDEBUG
     cerr << "Unknown constant type: " << *CPV << "\n";
-    abort();
+#endif
+    llvm_unreachable();
   }
 }
 
@@ -1456,10 +1465,9 @@
   const Type *Ty = I.getType();
   if (Ty->isInteger() && (Ty!=Type::Int1Ty && Ty!=Type::Int8Ty &&
         Ty!=Type::Int16Ty && Ty!=Type::Int32Ty && Ty!=Type::Int64Ty)) {
-      cerr << "The C backend does not currently support integer "
-           << "types of widths other than 1, 8, 16, 32, 64.\n";
-      cerr << "This is being tracked as PR 4158.\n";
-      abort();
+      llvm_report_error("The C backend does not currently support integer "
+                        "types of widths other than 1, 8, 16, 32, 64.\n"
+                        "This is being tracked as PR 4158.");
   }
 
   // If this is a non-trivial bool computation, make sure to truncate down to
@@ -2663,7 +2671,11 @@
     case Instruction::Shl : Out << " << "; break;
     case Instruction::LShr:
     case Instruction::AShr: Out << " >> "; break;
-    default: cerr << "Invalid operator type!" << I; abort();
+    default: 
+#ifndef NDEBUG
+       cerr << "Invalid operator type!" << I;
+#endif
+       llvm_unreachable();
     }
 
     writeOperandWithCast(I.getOperand(1), I.getOpcode());
@@ -2700,7 +2712,11 @@
   case ICmpInst::ICMP_SLT: Out << " < "; break;
   case ICmpInst::ICMP_UGT:
   case ICmpInst::ICMP_SGT: Out << " > "; break;
-  default: cerr << "Invalid icmp predicate!" << I; abort();
+  default:
+#ifndef NDEBUG
+    cerr << "Invalid icmp predicate!" << I; 
+#endif
+    llvm_unreachable();
   }
 
   writeOperandWithCast(I.getOperand(1), I);
@@ -3020,10 +3036,12 @@
     Out << ", ";
     // Output the last argument to the enclosing function.
     if (I.getParent()->getParent()->arg_empty()) {
-      cerr << "The C backend does not currently support zero "
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "The C backend does not currently support zero "
            << "argument varargs functions, such as '"
-           << I.getParent()->getParent()->getName() << "'!\n";
-      abort();
+           << I.getParent()->getParent()->getName() << "'!";
+      llvm_report_error(Msg.str());
     }
     writeOperand(--I.getParent()->getParent()->arg_end());
     Out << ')';
diff --git a/lib/Target/CellSPU/AsmPrinter/SPUAsmPrinter.cpp b/lib/Target/CellSPU/AsmPrinter/SPUAsmPrinter.cpp
index 2847d0b..4d51643 100644
--- a/lib/Target/CellSPU/AsmPrinter/SPUAsmPrinter.cpp
+++ b/lib/Target/CellSPU/AsmPrinter/SPUAsmPrinter.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmInfo.h"
@@ -319,8 +320,7 @@
 void SPUAsmPrinter::printOp(const MachineOperand &MO) {
   switch (MO.getType()) {
   case MachineOperand::MO_Immediate:
-    cerr << "printOp() does not handle immediate values\n";
-    abort();
+    llvm_report_error("printOp() does not handle immediate values");
     return;
 
   case MachineOperand::MO_MachineBasicBlock:
@@ -573,8 +573,7 @@
    case GlobalValue::InternalLinkage:
     break;
    default:
-    cerr << "Unknown linkage type!";
-    abort();
+    llvm_report_error("Unknown linkage type!");
   }
 
   EmitAlignment(Align, GVar);
diff --git a/lib/Target/CellSPU/SPUISelDAGToDAG.cpp b/lib/Target/CellSPU/SPUISelDAGToDAG.cpp
index 779d75d..f9801d5 100644
--- a/lib/Target/CellSPU/SPUISelDAGToDAG.cpp
+++ b/lib/Target/CellSPU/SPUISelDAGToDAG.cpp
@@ -31,8 +31,10 @@
 #include "llvm/GlobalValue.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
@@ -191,10 +193,11 @@
 
 #ifndef NDEBUG
     if (retval == 0) {
-      cerr << "SPUISelDAGToDAG.cpp: getValueTypeMapEntry returns NULL for "
-           << VT.getMVTString()
-           << "\n";
-      abort();
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "SPUISelDAGToDAG.cpp: getValueTypeMapEntry returns NULL for "
+           << VT.getMVTString();
+      llvm_report_error(Msg.str());
     }
 #endif
 
@@ -437,16 +440,14 @@
   case ISD::Constant:
   case ISD::ConstantPool:
   case ISD::GlobalAddress:
-    cerr << "SPU SelectAFormAddr: Constant/Pool/Global not lowered.\n";
-    abort();
+    llvm_report_error("SPU SelectAFormAddr: Constant/Pool/Global not lowered.");
     /*NOTREACHED*/
 
   case ISD::TargetConstant:
   case ISD::TargetGlobalAddress:
   case ISD::TargetJumpTable:
-    cerr << "SPUSelectAFormAddr: Target Constant/Pool/Global not wrapped as "
-         << "A-form address.\n";
-    abort();
+    llvm_report_error("SPUSelectAFormAddr: Target Constant/Pool/Global "
+                      "not wrapped as A-form address.");
     /*NOTREACHED*/
 
   case SPUISD::AFormAddr:
@@ -730,10 +731,8 @@
 
     switch (Op0VT.getSimpleVT()) {
     default:
-      cerr << "CellSPU Select: Unhandled zero/any extend MVT\n";
-      abort();
+      llvm_report_error("CellSPU Select: Unhandled zero/any extend MVT");
       /*NOTREACHED*/
-      break;
     case MVT::i32:
       shufMask = CurDAG->getNode(ISD::BUILD_VECTOR, dl, MVT::v4i32,
                                  CurDAG->getConstant(0x80808080, MVT::i32),
@@ -900,10 +899,11 @@
     const valtype_map_s *vtm = getValueTypeMapEntry(VT);
 
     if (vtm->ldresult_ins == 0) {
-      cerr << "LDRESULT for unsupported type: "
-           << VT.getMVTString()
-           << "\n";
-      abort();
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "LDRESULT for unsupported type: "
+           << VT.getMVTString();
+      llvm_report_error(Msg.str());
     }
 
     Opc = vtm->ldresult_ins;
@@ -1231,8 +1231,8 @@
     return CurDAG->getTargetNode(SPU::ORi64_v2i64, dl, OpVT,
                                  SDValue(emitBuildVector(i64vec), 0));
   } else {
-    cerr << "SPUDAGToDAGISel::SelectI64Constant: Unhandled i64vec condition\n";
-    abort();
+    llvm_report_error("SPUDAGToDAGISel::SelectI64Constant: Unhandled i64vec"
+                      "condition");
   }
 }
 
diff --git a/lib/Target/CellSPU/SPUISelLowering.cpp b/lib/Target/CellSPU/SPUISelLowering.cpp
index d8a7776..7879007 100644
--- a/lib/Target/CellSPU/SPUISelLowering.cpp
+++ b/lib/Target/CellSPU/SPUISelLowering.cpp
@@ -28,7 +28,9 @@
 #include "llvm/Function.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetOptions.h"
 
 #include <map>
@@ -70,10 +72,11 @@
 
 #ifndef NDEBUG
     if (retval == 0) {
-      cerr << "getValueTypeMapEntry returns NULL for "
-           << VT.getMVTString()
-           << "\n";
-      abort();
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "getValueTypeMapEntry returns NULL for "
+           << VT.getMVTString();
+      llvm_report_error(Msg.str());
     }
 #endif
 
@@ -665,11 +668,15 @@
   case ISD::POST_INC:
   case ISD::POST_DEC:
   case ISD::LAST_INDEXED_MODE:
-    cerr << "LowerLOAD: Got a LoadSDNode with an addr mode other than "
+    {
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "LowerLOAD: Got a LoadSDNode with an addr mode other than "
             "UNINDEXED\n";
-    cerr << (unsigned) LN->getAddressingMode() << "\n";
-    abort();
-    /*NOTREACHED*/
+      Msg << (unsigned) LN->getAddressingMode();
+      llvm_report_error(Msg.str());
+      /*NOTREACHED*/
+    }
   }
 
   return SDValue();
@@ -830,11 +837,15 @@
   case ISD::POST_INC:
   case ISD::POST_DEC:
   case ISD::LAST_INDEXED_MODE:
-    cerr << "LowerLOAD: Got a LoadSDNode with an addr mode other than "
+    {
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "LowerLOAD: Got a LoadSDNode with an addr mode other than "
             "UNINDEXED\n";
-    cerr << (unsigned) SN->getAddressingMode() << "\n";
-    abort();
-    /*NOTREACHED*/
+      Msg << (unsigned) SN->getAddressingMode();
+      llvm_report_error(Msg.str());
+      /*NOTREACHED*/
+    }
   }
 
   return SDValue();
@@ -920,9 +931,8 @@
       return DAG.getNode(SPUISD::IndirectAddr, dl, PtrVT, Hi, Lo);
     }
   } else {
-    cerr << "LowerGlobalAddress: Relocation model other than static not "
-         << "supported.\n";
-    abort();
+    llvm_report_error("LowerGlobalAddress: Relocation model other than static"
+                      "not supported.");
     /*NOTREACHED*/
   }
 
@@ -984,10 +994,11 @@
 
       switch (ObjectVT.getSimpleVT()) {
       default: {
-        cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
-             << ObjectVT.getMVTString()
-             << "\n";
-        abort();
+        std::string msg;
+        raw_string_ostream Msg(msg);
+        Msg << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
+             << ObjectVT.getMVTString();
+        llvm_report_error(Msg.str());
       }
       case MVT::i8:
         ArgRegClass = &SPU::R8CRegClass;
@@ -1529,12 +1540,14 @@
   uint64_t SplatBits = APSplatBits.getZExtValue();
 
   switch (VT.getSimpleVT()) {
-  default:
-    cerr << "CellSPU: Unhandled VT in LowerBUILD_VECTOR, VT = "
-         << VT.getMVTString()
-         << "\n";
-    abort();
+  default: {
+    std::string msg;
+    raw_string_ostream Msg(msg);
+    Msg << "CellSPU: Unhandled VT in LowerBUILD_VECTOR, VT = "
+         << VT.getMVTString();
+    llvm_report_error(Msg.str());
     /*NOTREACHED*/
+  }
   case MVT::v4f32: {
     uint32_t Value32 = uint32_t(SplatBits);
     assert(SplatBitSize == 32
@@ -1948,8 +1961,8 @@
     // slot 0 across the vector
     MVT VecVT = N.getValueType();
     if (!VecVT.isSimple() || !VecVT.isVector() || !VecVT.is128BitVector()) {
-      cerr << "LowerEXTRACT_VECTOR_ELT: Must have a simple, 128-bit vector type!\n";
-      abort();
+      llvm_report_error("LowerEXTRACT_VECTOR_ELT: Must have a simple, 128-bit"
+                        "vector type!");
     }
 
     // Make life easier by making sure the index is zero-extended to i32
@@ -1976,8 +1989,8 @@
 
     switch (VT.getSimpleVT()) {
     default:
-      cerr << "LowerEXTRACT_VECTOR_ELT(varable): Unhandled vector type\n";
-      abort();
+      llvm_report_error("LowerEXTRACT_VECTOR_ELT(varable): Unhandled vector"
+                        "type");
       /*NOTREACHED*/
     case MVT::i8: {
       SDValue factor = DAG.getConstant(0x00000000, MVT::i32);
@@ -2458,9 +2471,7 @@
   case ISD::SETONE:
     compareOp = ISD::SETNE; break;
   default:
-    cerr << "CellSPU ISel Select: unimplemented f64 condition\n";
-    abort();
-    break;
+    llvm_report_error("CellSPU ISel Select: unimplemented f64 condition");
   }
 
   SDValue result =
@@ -2568,11 +2579,13 @@
 
   switch (Opc) {
   default: {
+#ifndef NDEBUG
     cerr << "SPUTargetLowering::LowerOperation(): need to lower this!\n";
     cerr << "Op.getOpcode() = " << Opc << "\n";
     cerr << "*Op.getNode():\n";
     Op.getNode()->dump();
-    abort();
+#endif
+    llvm_unreachable();
   }
   case ISD::LOAD:
   case ISD::EXTLOAD:
diff --git a/lib/Target/CellSPU/SPUInstrInfo.cpp b/lib/Target/CellSPU/SPUInstrInfo.cpp
index e629c8d..eba1ca1 100644
--- a/lib/Target/CellSPU/SPUInstrInfo.cpp
+++ b/lib/Target/CellSPU/SPUInstrInfo.cpp
@@ -19,6 +19,7 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/Support/Streams.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 
 using namespace llvm;
 
@@ -313,8 +314,7 @@
   } else if (RC == SPU::VECREGRegisterClass) {
     opc = (isValidFrameIdx) ? SPU::STQDv16i8 : SPU::STQXv16i8;
   } else {
-    assert(0 && "Unknown regclass!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass!");
   }
 
   DebugLoc DL = DebugLoc::getUnknownLoc();
@@ -328,8 +328,7 @@
                                   SmallVectorImpl<MachineOperand> &Addr,
                                   const TargetRegisterClass *RC,
                                   SmallVectorImpl<MachineInstr*> &NewMIs) const {
-  cerr << "storeRegToAddr() invoked!\n";
-  abort();
+  llvm_report_error("storeRegToAddr() invoked!");
 
   if (Addr[0].isFI()) {
     /* do what storeRegToStackSlot does here */
@@ -348,8 +347,7 @@
     } else if (RC == SPU::VECREGRegisterClass) {
       /* Opc = PPC::STVX; */
     } else {
-      assert(0 && "Unknown regclass!");
-      abort();
+      LLVM_UNREACHABLE("Unknown regclass!");
     }
     DebugLoc DL = DebugLoc::getUnknownLoc();
     MachineInstrBuilder MIB = BuildMI(MF, DL, get(Opc))
@@ -385,8 +383,7 @@
   } else if (RC == SPU::VECREGRegisterClass) {
     opc = (isValidFrameIdx) ? SPU::LQDv16i8 : SPU::LQXv16i8;
   } else {
-    assert(0 && "Unknown regclass in loadRegFromStackSlot!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass in loadRegFromStackSlot!");
   }
 
   DebugLoc DL = DebugLoc::getUnknownLoc();
@@ -402,8 +399,7 @@
                                    const TargetRegisterClass *RC,
                                    SmallVectorImpl<MachineInstr*> &NewMIs)
     const {
-  cerr << "loadRegToAddr() invoked!\n";
-  abort();
+  llvm_report_error("loadRegToAddr() invoked!");
 
   if (Addr[0].isFI()) {
     /* do what loadRegFromStackSlot does here... */
@@ -424,8 +420,7 @@
     } else if (RC == SPU::GPRCRegisterClass) {
       /* Opc = something else! */
     } else {
-      assert(0 && "Unknown regclass!");
-      abort();
+      LLVM_UNREACHABLE("Unknown regclass!");
     }
     DebugLoc DL = DebugLoc::getUnknownLoc();
     MachineInstrBuilder MIB = BuildMI(MF, DL, get(Opc), DestReg);
diff --git a/lib/Target/CellSPU/SPURegisterInfo.cpp b/lib/Target/CellSPU/SPURegisterInfo.cpp
index e031048..31c75eb 100644
--- a/lib/Target/CellSPU/SPURegisterInfo.cpp
+++ b/lib/Target/CellSPU/SPURegisterInfo.cpp
@@ -35,7 +35,9 @@
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include <cstdlib>
@@ -176,8 +178,7 @@
   case SPU::R126: return 126;
   case SPU::R127: return 127;
   default:
-    cerr << "Unhandled reg in SPURegisterInfo::getRegisterNumbering!\n";
-    abort();
+    llvm_report_error("Unhandled reg in SPURegisterInfo::getRegisterNumbering");
   }
 }
 
@@ -485,8 +486,10 @@
         .addReg(SPU::R2)
         .addReg(SPU::R1);
     } else {
-      cerr << "Unhandled frame size: " << FrameSize << "\n";
-      abort();
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "Unhandled frame size: " << FrameSize;
+      llvm_report_error(Msg.str());
     }
 
     if (hasDebugInfo) {
@@ -577,8 +580,10 @@
         .addReg(SPU::R2)
         .addReg(SPU::R1);
     } else {
-      cerr << "Unhandled frame size: " << FrameSize << "\n";
-      abort();
+      std::string msg;
+      raw_string_ostream Msg(msg);
+      Msg << "Unhandled frame size: " << FrameSize;
+      llvm_report_error(Msg.str());
     }
    }
 }
diff --git a/lib/Target/IA64/AsmPrinter/IA64AsmPrinter.cpp b/lib/Target/IA64/AsmPrinter/IA64AsmPrinter.cpp
index 6faaf6c..111749e 100644
--- a/lib/Target/IA64/AsmPrinter/IA64AsmPrinter.cpp
+++ b/lib/Target/IA64/AsmPrinter/IA64AsmPrinter.cpp
@@ -318,11 +318,11 @@
    case GlobalValue::PrivateLinkage:
     break;
    case GlobalValue::GhostLinkage:
-    llvm_report_error("GhostLinkage cannot appear in IA64AsmPrinter!");
+    LLVM_UNREACHABLE("GhostLinkage cannot appear in IA64AsmPrinter!");
    case GlobalValue::DLLImportLinkage:
-    llvm_report_error("DLLImport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLImport linkage is not supported by this target!");
    case GlobalValue::DLLExportLinkage:
-    llvm_report_error("DLLExport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLExport linkage is not supported by this target!");
    default:
     LLVM_UNREACHABLE("Unknown linkage type!");
   }
diff --git a/lib/Target/IA64/IA64ISelDAGToDAG.cpp b/lib/Target/IA64/IA64ISelDAGToDAG.cpp
index 9800c50..739ae31 100644
--- a/lib/Target/IA64/IA64ISelDAGToDAG.cpp
+++ b/lib/Target/IA64/IA64ISelDAGToDAG.cpp
@@ -26,7 +26,9 @@
 #include "llvm/Intrinsics.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 namespace {
diff --git a/lib/Target/IA64/IA64ISelLowering.cpp b/lib/Target/IA64/IA64ISelLowering.cpp
index 3ef3dce..1b661eb 100644
--- a/lib/Target/IA64/IA64ISelLowering.cpp
+++ b/lib/Target/IA64/IA64ISelLowering.cpp
@@ -20,6 +20,7 @@
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Constants.h"
 #include "llvm/Function.h"
 using namespace llvm;
diff --git a/lib/Target/MSP430/MSP430ISelDAGToDAG.cpp b/lib/Target/MSP430/MSP430ISelDAGToDAG.cpp
index bf49ec0..6dd3b2a 100644
--- a/lib/Target/MSP430/MSP430ISelDAGToDAG.cpp
+++ b/lib/Target/MSP430/MSP430ISelDAGToDAG.cpp
@@ -28,6 +28,8 @@
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 /// MSP430DAGToDAGISel - MSP430 specific code to select MSP430 machine
diff --git a/lib/Target/MSP430/MSP430ISelLowering.cpp b/lib/Target/MSP430/MSP430ISelLowering.cpp
index 0fd96cc..10d4457 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -193,11 +193,11 @@
       switch (RegVT.getSimpleVT()) {
       default: 
         {
-          std::string msg;
-          raw_string_ostream Msg(msg);
-          Msg << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
-            << RegVT.getSimpleVT();
-          llvm_report_error(Msg.str());
+#ifndef NDEBUG
+          cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
+               << RegVT.getSimpleVT() << "\n";
+#endif
+          llvm_unreachable();
         }
       case MVT::i16:
         unsigned VReg =
diff --git a/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp b/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
index b2604e8..837e389 100644
--- a/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
+++ b/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
@@ -406,7 +406,7 @@
       break;
   
     default:
-      llvm_report_error("<unknown operand type>"); break;
+      LLVM_UNREACHABLE("<unknown operand type>");
   }
 
   if (closeP) O << ")";
@@ -545,11 +545,11 @@
       printSizeAndType = false;
     break;
    case GlobalValue::GhostLinkage:
-    llvm_report_error("Should not have any unmaterialized functions!");
+    LLVM_UNREACHABLE("Should not have any unmaterialized functions!");
    case GlobalValue::DLLImportLinkage:
-    llvm_report_error("DLLImport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLImport linkage is not supported by this target!");
    case GlobalValue::DLLExportLinkage:
-    llvm_report_error("DLLExport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLExport linkage is not supported by this target!");
    default:
     LLVM_UNREACHABLE("Unknown linkage type!");
   }
diff --git a/lib/Target/Mips/MipsISelDAGToDAG.cpp b/lib/Target/Mips/MipsISelDAGToDAG.cpp
index 53de1bb..bce8e3d 100644
--- a/lib/Target/Mips/MipsISelDAGToDAG.cpp
+++ b/lib/Target/Mips/MipsISelDAGToDAG.cpp
@@ -32,6 +32,8 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/PIC16/PIC16ISelDAGToDAG.cpp b/lib/Target/PIC16/PIC16ISelDAGToDAG.cpp
index 6c2b8ec..cc57d12 100644
--- a/lib/Target/PIC16/PIC16ISelDAGToDAG.cpp
+++ b/lib/Target/PIC16/PIC16ISelDAGToDAG.cpp
@@ -13,6 +13,8 @@
 
 #define DEBUG_TYPE "pic16-isel"
 
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "PIC16ISelDAGToDAG.h"
 #include "llvm/Support/Debug.h"
 
diff --git a/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp b/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
index 7f1673c..373a2ef 100644
--- a/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
@@ -36,6 +36,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmInfo.h"
@@ -70,7 +71,7 @@
 
     unsigned enumRegToMachineReg(unsigned enumReg) {
       switch (enumReg) {
-      default: assert(0 && "Unhandled register!"); break;
+      default: LLVM_UNREACHABLE("Unhandled register!");
       case PPC::CR0:  return  0;
       case PPC::CR1:  return  1;
       case PPC::CR2:  return  2;
@@ -80,7 +81,7 @@
       case PPC::CR6:  return  6;
       case PPC::CR7:  return  7;
       }
-      abort();
+      llvm_unreachable();
     }
 
     /// printInstruction - This method is automatically generated by tablegen
@@ -348,9 +349,7 @@
 void PPCAsmPrinter::printOp(const MachineOperand &MO) {
   switch (MO.getType()) {
   case MachineOperand::MO_Immediate:
-    cerr << "printOp() does not handle immediate values\n";
-    abort();
-    return;
+    LLVM_UNREACHABLE("printOp() does not handle immediate values");
 
   case MachineOperand::MO_MachineBasicBlock:
     printBasicBlockLabel(MO.getMBB());
@@ -552,9 +551,7 @@
   if (printInstruction(MI))
     return; // Printer was automatically generated
 
-  assert(0 && "Unhandled instruction in asm writer!");
-  abort();
-  return;
+  LLVM_UNREACHABLE("Unhandled instruction in asm writer!");
 }
 
 /// runOnMachineFunction - This uses the printMachineInstruction()
@@ -709,8 +706,7 @@
    case GlobalValue::PrivateLinkage:
     break;
    default:
-    cerr << "Unknown linkage type!";
-    abort();
+    LLVM_UNREACHABLE("Unknown linkage type!");
   }
 
   EmitAlignment(Align, GVar);
@@ -940,8 +936,7 @@
    case GlobalValue::PrivateLinkage:
     break;
    default:
-    cerr << "Unknown linkage type!";
-    abort();
+    LLVM_UNREACHABLE("Unknown linkage type!");
   }
 
   EmitAlignment(Align, GVar);
diff --git a/lib/Target/PowerPC/PPCCodeEmitter.cpp b/lib/Target/PowerPC/PPCCodeEmitter.cpp
index eaa8269..c191f65 100644
--- a/lib/Target/PowerPC/PPCCodeEmitter.cpp
+++ b/lib/Target/PowerPC/PPCCodeEmitter.cpp
@@ -26,6 +26,8 @@
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
@@ -263,8 +265,10 @@
     MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(),
                                                Reloc, MO.getMBB()));
   } else {
+#ifndef NDEBUG
     cerr << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
-    abort();
+#endif
+    llvm_unreachable();
   }
 
   return rv;
diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 823e316..398a1fe 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -31,6 +31,8 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 namespace {
@@ -600,8 +602,8 @@
   case ISD::SETONE:
   case ISD::SETOLE:
   case ISD::SETOGE:
-    assert(0 && "Should be lowered by legalize!");
-  default: assert(0 && "Unknown condition!"); abort();
+    LLVM_UNREACHABLE("Should be lowered by legalize!");
+  default: LLVM_UNREACHABLE("Unknown condition!");
   case ISD::SETOEQ:
   case ISD::SETEQ:  return PPC::PRED_EQ;
   case ISD::SETUNE:
@@ -632,7 +634,7 @@
   Invert = false;
   Other = -1;
   switch (CC) {
-  default: assert(0 && "Unknown condition!"); abort();
+  default: LLVM_UNREACHABLE("Unknown condition!");
   case ISD::SETOLT:
   case ISD::SETLT:  return 0;                  // Bit #0 = SETOLT
   case ISD::SETOGT:
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 1c6b287..5b0c935 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -32,6 +32,8 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/DerivedTypes.h"
 using namespace llvm;
 
@@ -2584,9 +2586,11 @@
       }
       
       if (Result) {
+#ifndef NDEBUG
         cerr << "Call operand #" << i << " has unhandled type "
              << ArgVT.getMVTString() << "\n";
-        abort();
+#endif
+        llvm_unreachable();
       }
     }
   } else {
@@ -4141,8 +4145,7 @@
     }
     return DAG.getVectorShuffle(MVT::v16i8, dl, EvenParts, OddParts, Ops);
   } else {
-    assert(0 && "Unknown mul to lower!");
-    abort();
+    LLVM_UNREACHABLE("Unknown mul to lower!");
   }
 }
 
diff --git a/lib/Target/PowerPC/PPCInstrInfo.cpp b/lib/Target/PowerPC/PPCInstrInfo.cpp
index 87c612a..63adf32 100644
--- a/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -20,6 +20,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmInfo.h"
 using namespace llvm;
 
@@ -485,8 +487,7 @@
                      .addReg(PPC::R0)
                      .addReg(PPC::R0));
   } else {
-    assert(0 && "Unknown regclass!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass!");
   }
 
   return false;
@@ -537,8 +538,7 @@
   } else if (RC == PPC::VRRCRegisterClass) {
     Opc = PPC::STVX;
   } else {
-    assert(0 && "Unknown regclass!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass!");
   }
   MachineInstrBuilder MIB = BuildMI(MF, DL, get(Opc))
     .addReg(SrcReg, getKillRegState(isKill));
@@ -634,8 +634,7 @@
     NewMIs.push_back(BuildMI(MF, DL, get(PPC::LVX),DestReg).addReg(PPC::R0)
                      .addReg(PPC::R0));
   } else {
-    assert(0 && "Unknown regclass!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass!");
   }
 }
 
@@ -677,8 +676,7 @@
   } else if (RC == PPC::VRRCRegisterClass) {
     Opc = PPC::LVX;
   } else {
-    assert(0 && "Unknown regclass!");
-    abort();
+    LLVM_UNREACHABLE("Unknown regclass!");
   }
   DebugLoc DL = DebugLoc::getUnknownLoc();
   MachineInstrBuilder MIB = BuildMI(MF, DL, get(Opc), DestReg);
diff --git a/lib/Target/PowerPC/PPCJITInfo.cpp b/lib/Target/PowerPC/PPCJITInfo.cpp
index 7486d74..25f3785 100644
--- a/lib/Target/PowerPC/PPCJITInfo.cpp
+++ b/lib/Target/PowerPC/PPCJITInfo.cpp
@@ -18,6 +18,8 @@
 #include "llvm/Function.h"
 #include "llvm/System/Memory.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 static TargetJITInfo::JITCompilerFn JITCompilerFunction;
@@ -197,8 +199,7 @@
     );
 #else
 void PPC32CompilationCallback() {
-  assert(0 && "This is not a power pc, you can't execute this!");
-  abort();
+  LLVM_UNREACHABLE("This is not a power pc, you can't execute this!");
 }
 #endif
 
@@ -264,8 +265,7 @@
     );
 #else
 void PPC64CompilationCallback() {
-  assert(0 && "This is not a power pc, you can't execute this!");
-  abort();
+  LLVM_UNREACHABLE("This is not a power pc, you can't execute this!");
 }
 #endif
 
diff --git a/lib/Target/PowerPC/PPCRegisterInfo.cpp b/lib/Target/PowerPC/PPCRegisterInfo.cpp
index 97b1c57..26d08d0 100644
--- a/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -37,7 +37,9 @@
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include <cstdlib>
@@ -111,8 +113,7 @@
   case R30:  case X30:  case F30:  case V30: case CR7EQ: return 30;
   case R31:  case X31:  case F31:  case V31: case CR7UN: return 31;
   default:
-    cerr << "Unhandled reg in PPCRegisterInfo::getRegisterNumbering!\n";
-    abort();
+    LLVM_UNREACHABLE("Unhandled reg in PPCRegisterInfo::getRegisterNumbering!");
   }
 }
 
diff --git a/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp b/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
index 9432ff0..04e1cc8 100644
--- a/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
+++ b/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
@@ -185,7 +185,7 @@
       << MO.getIndex();
     break;
   default:
-    llvm_report_error("<unknown operand type>"); break;
+    LLVM_UNREACHABLE("<unknown operand type>");
   }
   if (CloseParen) O << ")";
 }
@@ -299,11 +299,11 @@
    case GlobalValue::InternalLinkage:
     break;
    case GlobalValue::GhostLinkage:
-    llvm_report_error("Should not have any unmaterialized functions!");
+    LLVM_UNREACHABLE("Should not have any unmaterialized functions!");
    case GlobalValue::DLLImportLinkage:
-    llvm_report_error("DLLImport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLImport linkage is not supported by this target!");
    case GlobalValue::DLLExportLinkage:
-    llvm_report_error("DLLExport linkage is not supported by this target!");
+    LLVM_UNREACHABLE("DLLExport linkage is not supported by this target!");
    default:
     LLVM_UNREACHABLE("Unknown linkage type!");
   }
diff --git a/lib/Target/Sparc/SparcISelDAGToDAG.cpp b/lib/Target/Sparc/SparcISelDAGToDAG.cpp
index c9bd62d..e1b9b59 100644
--- a/lib/Target/Sparc/SparcISelDAGToDAG.cpp
+++ b/lib/Target/Sparc/SparcISelDAGToDAG.cpp
@@ -17,6 +17,8 @@
 #include "llvm/CodeGen/SelectionDAGISel.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/X86/AsmPrinter/X86ATTInstPrinter.cpp b/lib/Target/X86/AsmPrinter/X86ATTInstPrinter.cpp
index 4f7a00a..5b10c7b 100644
--- a/lib/Target/X86/AsmPrinter/X86ATTInstPrinter.cpp
+++ b/lib/Target/X86/AsmPrinter/X86ATTInstPrinter.cpp
@@ -104,7 +104,7 @@
     if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg()))
       O << DispVal;
   } else {
-    llvm_report_error("non-immediate displacement for LEA?");
+    LLVM_UNREACHABLE("non-immediate displacement for LEA?");
     //assert(DispSpec.isGlobal() || DispSpec.isCPI() ||
     //       DispSpec.isJTI() || DispSpec.isSymbol());
     //printOperand(MI, Op+3, "mem");
diff --git a/lib/Target/X86/X86CodeEmitter.cpp b/lib/Target/X86/X86CodeEmitter.cpp
index afb1e1d..1dc6e76 100644
--- a/lib/Target/X86/X86CodeEmitter.cpp
+++ b/lib/Target/X86/X86CodeEmitter.cpp
@@ -32,7 +32,6 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
@@ -806,10 +805,10 @@
   }
 
   if (!Desc->isVariadic() && CurOp != NumOps) {
-    std::string msg;
-    raw_string_ostream Msg(msg);
-    Msg << "Cannot encode: " << MI;
-    llvm_report_error(Msg.str());
+#ifndef NDEBUG
+    cerr << "Cannot encode: " << MI << "\n";
+#endif
+    llvm_unreachable();
   }
 }
 
diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 1336177..b8cbbfa 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -35,8 +35,10 @@
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Streams.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
 using namespace llvm;
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 33789ce..32f247d 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -38,6 +38,7 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 static cl::opt<bool>
@@ -6054,7 +6055,7 @@
   SDValue SrcPtr = Op.getOperand(1);
   SDValue SrcSV = Op.getOperand(2);
 
-  LLVM_UNREACHABLE("VAArgInst is not yet implemented for x86-64!");
+  llvm_report_error("VAArgInst is not yet implemented for x86-64!");
   return SDValue();
 }
 
diff --git a/lib/Target/XCore/XCoreAsmPrinter.cpp b/lib/Target/XCore/XCoreAsmPrinter.cpp
index 1b7238c..6f2af77 100644
--- a/lib/Target/XCore/XCoreAsmPrinter.cpp
+++ b/lib/Target/XCore/XCoreAsmPrinter.cpp
@@ -204,13 +204,13 @@
     case GlobalValue::PrivateLinkage:
       break;
     case GlobalValue::GhostLinkage:
-      llvm_report_error("Should not have any unmaterialized functions!");
+      LLVM_UNREACHABLE("Should not have any unmaterialized functions!");
     case GlobalValue::DLLImportLinkage:
-      llvm_report_error("DLLImport linkage is not supported by this target!");
+      LLVM_UNREACHABLE("DLLImport linkage is not supported by this target!");
     case GlobalValue::DLLExportLinkage:
-      llvm_report_error("DLLExport linkage is not supported by this target!");
+      LLVM_UNREACHABLE("DLLExport linkage is not supported by this target!");
     default:
-      assert(0 && "Unknown linkage type!");
+      LLVM_UNREACHABLE("Unknown linkage type!");
     }
 
     EmitAlignment(Align, GV, 2);
diff --git a/lib/Target/XCore/XCoreISelDAGToDAG.cpp b/lib/Target/XCore/XCoreISelDAGToDAG.cpp
index eed34a4..5114bc7 100644
--- a/lib/Target/XCore/XCoreISelDAGToDAG.cpp
+++ b/lib/Target/XCore/XCoreISelDAGToDAG.cpp
@@ -28,6 +28,8 @@
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 #include <queue>
 #include <set>
 using namespace llvm;
diff --git a/lib/Target/XCore/XCoreISelLowering.cpp b/lib/Target/XCore/XCoreISelLowering.cpp
index 7d0de2a..c615d61 100644
--- a/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/lib/Target/XCore/XCoreISelLowering.cpp
@@ -32,6 +32,7 @@
 #include "llvm/CodeGen/SelectionDAGISel.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/ADT/VectorExtras.h"
 #include <queue>
 #include <set>
@@ -270,8 +271,11 @@
   }
   const Type *Ty = cast<PointerType>(GV->getType())->getElementType();
   if (!Ty->isSized() || isZeroLengthArray(Ty)) {
-    llvm_report_error("Size of thread local object " + GVar->getName()
-                      + " is unknown");
+#ifndef NDEBUG
+    cerr << "Size of thread local object " << GVar->getName()
+        << " is unknown\n";
+#endif
+    llvm_unreachable();
   }
   SDValue base = getGlobalAddressWrapper(GA, GV, DAG);
   const TargetData *TD = TM.getTargetData();
@@ -646,11 +650,11 @@
       switch (RegVT.getSimpleVT()) {
       default:
         {
-          std::string msg;
-          raw_string_ostream Msg(msg);
-          Msg << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
-            << RegVT.getSimpleVT();
-          llvm_report_error(Msg.str());
+#ifndef NDEBUG
+          cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
+               << RegVT.getSimpleVT() << "\n";
+#endif
+          llvm_unreachable();
         }
       case MVT::i32:
         unsigned VReg = RegInfo.createVirtualRegister(
diff --git a/lib/Target/XCore/XCoreRegisterInfo.cpp b/lib/Target/XCore/XCoreRegisterInfo.cpp
index ffbace6..9bf99ac 100644
--- a/lib/Target/XCore/XCoreRegisterInfo.cpp
+++ b/lib/Target/XCore/XCoreRegisterInfo.cpp
@@ -144,11 +144,11 @@
       
       if (!isU6 && !isImmU16(Amount)) {
         // FIX could emit multiple instructions in this case.
-        std::string msg;
-        raw_string_ostream Msg(msg);
-        Msg  << "eliminateCallFramePseudoInstr size too big: "
-             << Amount;
-        llvm_report_error(Msg.str());
+#ifndef NDEBUG
+        cerr << "eliminateCallFramePseudoInstr size too big: "
+             << Amount << "\n";
+#endif
+        llvm_unreachable();
       }
 
       MachineInstr *New;
diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index 70c27eb..ec29917 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Streams.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cctype>
@@ -1235,7 +1236,7 @@
   case GlobalValue::ExternalWeakLinkage: Out << "extern_weak "; break;
   case GlobalValue::ExternalLinkage: break;
   case GlobalValue::GhostLinkage:
-    llvm_report_error("GhostLinkage not allowed in AsmWriter!");
+    LLVM_UNREACHABLE("GhostLinkage not allowed in AsmWriter!");
   }
 }
 
diff --git a/lib/VMCore/Globals.cpp b/lib/VMCore/Globals.cpp
index b3087f7..c3fe568 100644
--- a/lib/VMCore/Globals.cpp
+++ b/lib/VMCore/Globals.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LeakDetector.h"
+#include "llvm/Support/Streams.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp
index 6626930..bbb22c5 100644
--- a/lib/VMCore/Instructions.cpp
+++ b/lib/VMCore/Instructions.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/ConstantRange.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Streams.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/VMCore/Type.cpp b/lib/VMCore/Type.cpp
index 432a1cc..8daaf91 100644
--- a/lib/VMCore/Type.cpp
+++ b/lib/VMCore/Type.cpp
@@ -265,10 +265,10 @@
 }
 
 void Type::refineAbstractType(const DerivedType *OldTy, const Type *NewTy) {
-  llvm_report_error("Attempting to refine a derived type!");
+  LLVM_UNREACHABLE("Attempting to refine a derived type!");
 }
 void Type::typeBecameConcrete(const DerivedType *AbsTy) {
-  llvm_report_error("DerivedType is already a concrete type!");
+  LLVM_UNREACHABLE("DerivedType is already a concrete type!");
 }
 
 
diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp
index 8c5d551..0120333 100644
--- a/lib/VMCore/Value.cpp
+++ b/lib/VMCore/Value.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/ValueHandle.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/System/RWMutex.h"
 #include "llvm/System/Threading.h"
 #include "llvm/ADT/DenseMap.h"
@@ -515,8 +516,8 @@
       cerr << "While deleting: " << *V->getType() << " %" << V->getNameStr()
            << "\n";
 #endif
-      llvm_report_error("An asserting value handle still pointed to this"
-                        "value!");
+      LLVM_UNREACHABLE("An asserting value handle still pointed to this"
+                       "value!");
     case Weak:
       // Weak just goes to null, which will unlink it from the list.
       ThisNode->operator=(0);
diff --git a/lib/VMCore/Verifier.cpp b/lib/VMCore/Verifier.cpp
index 6674acb..da3fed0 100644
--- a/lib/VMCore/Verifier.cpp
+++ b/lib/VMCore/Verifier.cpp
@@ -211,7 +211,9 @@
       default: assert(0 && "Unknown action");
       case AbortProcessAction:
         msgs << "compilation aborted!\n";
-        llvm_report_error(msgs.str());
+        cerr << msgs.str();
+        // Client should choose different reaction if abort is not desired
+        abort();
       case PrintMessageAction:
         msgs << "verification continues.\n";
         cerr << msgs.str();