Index: include/llvm/MC/MCInstPrinter.h
===================================================================
--- include/llvm/MC/MCInstPrinter.h
+++ include/llvm/MC/MCInstPrinter.h
@@ -64,6 +64,10 @@
 
   virtual ~MCInstPrinter();
 
+  /// Customize the printer according to a command line option.
+  /// @return true if the option is recognized and applied.
+  virtual bool applyTargetSpecificCLOption(StringRef Opt) { return false; }
+
   /// Specify a stream to emit comments to.
   void setCommentStream(raw_ostream &OS) { CommentStream = &OS; }
 
Index: include/llvm/Target/Target.td
===================================================================
--- include/llvm/Target/Target.td
+++ include/llvm/Target/Target.td
@@ -121,6 +121,10 @@
 // this register class when printing.
 class RegAltNameIndex {
   string Namespace = "";
+
+  // A set to be used if the name for a register is not defined in this set.
+  // This allows creating name sets with only a few alternative names.
+  RegAltNameIndex FallbackRegAltNameIndex = ?;
 }
 def NoRegAltName : RegAltNameIndex;
 
Index: lib/Target/ARM/ARMRegisterInfo.td
===================================================================
--- lib/Target/ARM/ARMRegisterInfo.td
+++ lib/Target/ARM/ARMRegisterInfo.td
@@ -13,7 +13,8 @@
 //===----------------------------------------------------------------------===//
 
 // Registers are identified with 4-bit ID numbers.
-class ARMReg<bits<16> Enc, string n, list<Register> subregs = []> : Register<n> {
+class ARMReg<bits<16> Enc, string n, list<Register> subregs = [],
+             list<string> altNames = []> : Register<n, altNames> {
   let HWEncoding = Enc;
   let Namespace = "ARM";
   let SubRegs = subregs;
@@ -26,6 +27,11 @@
   let Namespace = "ARM";
 }
 
+let Namespace = "ARM",
+    FallbackRegAltNameIndex = NoRegAltName in {
+  def RegNamesRaw : RegAltNameIndex;
+}
+
 // Subregister indices.
 let Namespace = "ARM" in {
 def qqsub_0 : SubRegIndex<256>;
@@ -83,9 +89,11 @@
 def R10 : ARMReg<10, "r10">, DwarfRegNum<[10]>;
 def R11 : ARMReg<11, "r11">, DwarfRegNum<[11]>;
 def R12 : ARMReg<12, "r12">, DwarfRegNum<[12]>;
-def SP  : ARMReg<13, "sp">,  DwarfRegNum<[13]>;
-def LR  : ARMReg<14, "lr">,  DwarfRegNum<[14]>;
-def PC  : ARMReg<15, "pc">,  DwarfRegNum<[15]>;
+let RegAltNameIndices = [RegNamesRaw] in {
+def SP  : ARMReg<13, "sp", [], ["r13"]>,  DwarfRegNum<[13]>;
+def LR  : ARMReg<14, "lr", [], ["r14"]>,  DwarfRegNum<[14]>;
+def PC  : ARMReg<15, "pc", [], ["r15"]>,  DwarfRegNum<[15]>;
+}
 }
 
 // Float registers
Index: lib/Target/ARM/InstPrinter/ARMInstPrinter.h
===================================================================
--- lib/Target/ARM/InstPrinter/ARMInstPrinter.h
+++ lib/Target/ARM/InstPrinter/ARMInstPrinter.h
@@ -13,6 +13,7 @@
 #ifndef LLVM_LIB_TARGET_ARM_INSTPRINTER_ARMINSTPRINTER_H
 #define LLVM_LIB_TARGET_ARM_INSTPRINTER_ARMINSTPRINTER_H
 
+#include "MCTargetDesc/ARMMCTargetDesc.h"
 #include "llvm/MC/MCInstPrinter.h"
 
 namespace llvm {
@@ -22,6 +23,8 @@
   ARMInstPrinter(const MCAsmInfo &MAI, const MCInstrInfo &MII,
                  const MCRegisterInfo &MRI);
 
+  bool applyTargetSpecificCLOption(StringRef Opt) override;
+
   void printInst(const MCInst *MI, raw_ostream &O, StringRef Annot,
                  const MCSubtargetInfo &STI) override;
   void printRegName(raw_ostream &OS, unsigned RegNo) const override;
@@ -35,7 +38,8 @@
                                        unsigned PrintMethodIdx,
                                        const MCSubtargetInfo &STI,
                                        raw_ostream &O);
-  static const char *getRegisterName(unsigned RegNo);
+  static const char *getRegisterName(unsigned RegNo,
+                                     unsigned AltIdx = ARM::NoRegAltName);
 
   void printOperand(const MCInst *MI, unsigned OpNo, const MCSubtargetInfo &STI,
                     raw_ostream &O);
@@ -235,6 +239,9 @@
   template<int64_t Angle, int64_t Remainder>
   void printComplexRotationOp(const MCInst *MI, unsigned OpNum,
                               const MCSubtargetInfo &STI, raw_ostream &O);
+
+private:
+  unsigned DefaultAltIdx = ARM::NoRegAltName;
 };
 
 } // end namespace llvm
Index: lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
===================================================================
--- lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
+++ lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
@@ -72,8 +72,20 @@
                                const MCRegisterInfo &MRI)
     : MCInstPrinter(MAI, MII, MRI) {}
 
+bool ARMInstPrinter::applyTargetSpecificCLOption(StringRef Opt) {
+  if (Opt == "reg-names-std") {
+    DefaultAltIdx = ARM::NoRegAltName;
+    return true;
+  }
+  if (Opt == "reg-names-raw") {
+    DefaultAltIdx = ARM::RegNamesRaw;
+    return true;
+  }
+  return false;
+}
+
 void ARMInstPrinter::printRegName(raw_ostream &OS, unsigned RegNo) const {
-  OS << markup("<reg:") << getRegisterName(RegNo) << markup(">");
+  OS << markup("<reg:") << getRegisterName(RegNo, DefaultAltIdx) << markup(">");
 }
 
 void ARMInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
Index: test/tools/llvm-objdump/ARM/reg-names.s
===================================================================
--- /dev/null
+++ test/tools/llvm-objdump/ARM/reg-names.s
@@ -0,0 +1,17 @@
+@ RUN: llvm-mc %s -triple armv5-unknown-linux -filetype=obj -o %t
+@ RUN: llvm-objdump -d %t | FileCheck -check-prefix=STD %s
+@ RUN: llvm-objdump -d -Mreg-names-std %t \
+@ RUN:   | FileCheck -check-prefix=STD %s
+@ RUN: llvm-objdump -d --disassembler-options=reg-names-raw %t \
+@ RUN:   | FileCheck -check-prefix=RAW %s
+@ RUN: llvm-objdump -d --disassembler-options reg-names-raw %t \
+@ RUN:   | FileCheck -check-prefix=RAW %s
+@ RUN: llvm-objdump -d -Mreg-names-raw,reg-names-std %t \
+@ RUN:   | FileCheck -check-prefix=STD %s
+@ RUN: llvm-objdump -d -Mreg-names-std,reg-names-raw %t \
+@ RUN:   | FileCheck -check-prefix=RAW %s
+
+.text
+  add r13, r14, r15
+@ STD: add sp, lr, pc
+@ RAW: add r13, r14, r15
Index: tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- tools/llvm-objdump/llvm-objdump.cpp
+++ tools/llvm-objdump/llvm-objdump.cpp
@@ -293,6 +293,15 @@
                                  cl::NotHidden, cl::Grouping,
                                  cl::aliasopt(DisassembleZeroes));
 
+static cl::list<std::string>
+    DisassemblerOptions("disassembler-options",
+                        cl::desc("Pass target specific disassembler options"),
+                        cl::value_desc("options"), cl::CommaSeparated);
+static cl::alias
+    DisassemblerOptionsShort("M", cl::desc("Alias for --disassembler-options"),
+                             cl::NotHidden, cl::Prefix, cl::CommaSeparated,
+                             cl::aliasopt(DisassemblerOptions));
+
 static StringRef ToolName;
 
 typedef std::vector<std::tuple<uint64_t, StringRef, uint8_t>> SectionSymbolsTy;
@@ -1473,6 +1482,10 @@
   PrettyPrinter &PIP = selectPrettyPrinter(Triple(TripleName));
   SourcePrinter SP(Obj, TheTarget->getName());
 
+  for (StringRef Opt : DisassemblerOptions)
+    if (!IP->applyTargetSpecificCLOption(Opt))
+      error("Unrecognized disassembler option: " + Opt);
+
   disassembleObject(TheTarget, Obj, Ctx, DisAsm.get(), MIA.get(), IP.get(),
                     STI.get(), PIP, SP, InlineRelocs);
 }
Index: utils/TableGen/AsmWriterEmitter.cpp
===================================================================
--- utils/TableGen/AsmWriterEmitter.cpp
+++ utils/TableGen/AsmWriterEmitter.cpp
@@ -585,11 +585,20 @@
       O << "  case ";
       if (!Namespace.empty())
         O << Namespace << "::";
-      O << AltName << ":\n"
-        << "    assert(*(AsmStrs" << AltName << "+RegAsmOffset" << AltName
-        << "[RegNo-1]) &&\n"
-        << "           \"Invalid alt name index for register!\");\n"
-        << "    return AsmStrs" << AltName << "+RegAsmOffset" << AltName
+      O << AltName << ":\n";
+      if (R->isValueUnset("FallbackRegAltNameIndex"))
+        O << "    assert(*(AsmStrs" << AltName << "+RegAsmOffset" << AltName
+          << "[RegNo-1]) &&\n"
+          << "           \"Invalid alt name index for register!\");\n";
+      else {
+        O << "    if (!*(AsmStrs" << AltName << "+RegAsmOffset" << AltName
+          << "[RegNo-1]))\n"
+          << "      return getRegisterName(RegNo, ";
+        if (!Namespace.empty())
+          O << Namespace << "::";
+        O << R->getValueAsDef("FallbackRegAltNameIndex")->getName() << ");\n";
+      }
+      O << "    return AsmStrs" << AltName << "+RegAsmOffset" << AltName
         << "[RegNo-1];\n";
     }
     O << "  }\n";