Index: include/llvm/CodeGen/AsmPrinter.h
===================================================================
--- include/llvm/CodeGen/AsmPrinter.h
+++ include/llvm/CodeGen/AsmPrinter.h
@@ -656,6 +656,8 @@
   void EmitLLVMUsedList(const ConstantArray *InitList);
   /// Emit llvm.ident metadata in an '.ident' directive.
   void EmitModuleIdents(Module &M);
+  /// Emit bytes for llvm.commandline metadata.
+  void EmitModuleCommandLines(Module &M);
   void EmitXXStructorList(const DataLayout &DL, const Constant *List,
                           bool isCtor);
 
Index: include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
===================================================================
--- include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
+++ include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
@@ -90,6 +90,8 @@
   const MCExpr *lowerRelativeReference(const GlobalValue *LHS,
                                        const GlobalValue *RHS,
                                        const TargetMachine &TM) const override;
+
+  MCSection *getSectionForCommandLines() const override;
 };
 
 class TargetLoweringObjectFileMachO : public TargetLoweringObjectFile {
Index: include/llvm/Target/TargetLoweringObjectFile.h
===================================================================
--- include/llvm/Target/TargetLoweringObjectFile.h
+++ include/llvm/Target/TargetLoweringObjectFile.h
@@ -201,6 +201,12 @@
   virtual void emitLinkerFlagsForUsed(raw_ostream &OS,
                                       const GlobalValue *GV) const {}
 
+  /// If supported, return the section to use for the llvm.commandline
+  /// metadata. Otherwise, return nullptr.
+  virtual MCSection *getSectionForCommandLines() const {
+    return nullptr;
+  }
+
 protected:
   virtual MCSection *SelectSectionForGlobal(const GlobalObject *GO,
                                             SectionKind Kind,
Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1500,6 +1500,9 @@
   // Emit llvm.ident metadata in an '.ident' directive.
   EmitModuleIdents(M);
 
+  // Emit bytes for llvm.commandline metadata.
+  EmitModuleCommandLines(M);
+
   // Emit __morestack address if needed for indirect calls.
   if (MMI->usesMorestackAddr()) {
     unsigned Align = 1;
@@ -2009,6 +2012,30 @@
   }
 }
 
+void AsmPrinter::EmitModuleCommandLines(Module &M) {
+  MCSection *CommandLine = getObjFileLowering().getSectionForCommandLines();
+  if (!CommandLine)
+    return;
+
+  if (const NamedMDNode *NMD = M.getNamedMetadata("llvm.commandline")) {
+    if (!NMD->getNumOperands())
+      return;
+
+    OutStreamer->PushSection();
+    OutStreamer->SwitchSection(CommandLine);
+    OutStreamer->EmitZeros(1);
+    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
+      const MDNode *N = NMD->getOperand(i);
+      assert(N->getNumOperands() == 1 &&
+             "llvm.commandline metadata entry can have only one operand");
+      const MDString *S = cast<MDString>(N->getOperand(0));
+      OutStreamer->EmitBytes(S->getString());
+      OutStreamer->EmitZeros(1);
+    }
+    OutStreamer->PopSection();
+  }
+}
+
 //===--------------------------------------------------------------------===//
 // Emission and print routines
 //
Index: lib/CodeGen/TargetLoweringObjectFileImpl.cpp
===================================================================
--- lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -795,6 +795,11 @@
       MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
 }
 
+MCSection *TargetLoweringObjectFileELF::getSectionForCommandLines() const {
+  return getContext().getELFSection(".LLVM.command.line", ELF::SHT_PROGBITS,
+                                    ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
+}
+
 void
 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
   UseInitArray = UseInitArray_;
Index: lib/IR/Verifier.cpp
===================================================================
--- lib/IR/Verifier.cpp
+++ lib/IR/Verifier.cpp
@@ -383,6 +383,7 @@
 
     visitModuleFlags(M);
     visitModuleIdents(M);
+    visitModuleCommandLines(M);
 
     verifyCompileUnits();
 
@@ -405,6 +406,7 @@
   void visitValueAsMetadata(const ValueAsMetadata &MD, Function *F);
   void visitComdat(const Comdat &C);
   void visitModuleIdents(const Module &M);
+  void visitModuleCommandLines(const Module &M);
   void visitModuleFlags(const Module &M);
   void visitModuleFlag(const MDNode *Op,
                        DenseMap<const MDString *, const MDNode *> &SeenIDs,
@@ -1303,6 +1305,24 @@
   }
 }
 
+void Verifier::visitModuleCommandLines(const Module &M) {
+  const NamedMDNode *CommandLines = M.getNamedMetadata("llvm.commandline");
+  if (!CommandLines)
+    return;
+
+  // llvm.commandline takes a list of metadata entry. Each entry has only one
+  // string. Scan each llvm.commandline entry and make sure that this
+  // requirement is met.
+  for (const MDNode *N : CommandLines->operands()) {
+    Assert(N->getNumOperands() == 1,
+           "incorrect number of operands in llvm.commandline metadata", N);
+    Assert(dyn_cast_or_null<MDString>(N->getOperand(0)),
+           ("invalid value for llvm.commandline metadata entry operand"
+            "(the operand should be a string)"),
+           N->getOperand(0));
+  }
+}
+
 void Verifier::visitModuleFlags(const Module &M) {
   const NamedMDNode *Flags = M.getModuleFlagsMetadata();
   if (!Flags) return;
Index: test/CodeGen/X86/commandline-metadata.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/commandline-metadata.ll
@@ -0,0 +1,13 @@
+; RUN: llc -mtriple=x86_64-linux < %s | FileCheck %s
+; Verify that llvm.commandline metadata is emitted to a section named
+; .LLVM.command.line with each line separated with null bytes.
+
+; CHECK: .section .LLVM.command.line,"MS",@progbits,1
+; CHECK-NEXT: .zero 1
+; CHECK-NEXT: .ascii "clang -command -line"
+; CHECK-NEXT: .zero 1
+; CHECK-NEXT: .ascii "something else"
+; CHECK-NEXT: .zero 1
+!llvm.commandline = !{!0, !1}
+!0 = !{!"clang -command -line"}
+!1 = !{!"something else"}
Index: test/Linker/Inputs/commandline.a.ll
===================================================================
--- /dev/null
+++ test/Linker/Inputs/commandline.a.ll
@@ -0,0 +1,3 @@
+!llvm.commandline = !{!0, !1}
+!0 = !{!"compiler -v1"}
+!1 = !{!"compiler -v2"}
Index: test/Linker/Inputs/commandline.b.ll
===================================================================
--- /dev/null
+++ test/Linker/Inputs/commandline.b.ll
@@ -0,0 +1,2 @@
+!llvm.commandline = !{!0}
+!0 = !{!"compiler -v3"}
Index: test/Linker/commandline.ll
===================================================================
--- /dev/null
+++ test/Linker/commandline.ll
@@ -0,0 +1,9 @@
+; RUN: llvm-link %S/Inputs/commandline.a.ll %S/Inputs/commandline.b.ll -S | FileCheck %s
+
+; Verify that multiple input llvm.commandline metadata are linked together.
+
+; CHECK-DAG: !llvm.commandline = !{!0, !1, !2}
+; CHECK-DAG: "compiler -v1"
+; CHECK-DAG: "compiler -v2"
+; CHECK-DAG: "compiler -v3"
+
Index: test/Verifier/commandline-meta1.ll
===================================================================
--- /dev/null
+++ test/Verifier/commandline-meta1.ll
@@ -0,0 +1,12 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; Verify that llvm.commandline is properly structured.
+; llvm.commandline takes a list of metadata entries.
+; Each metadata entry can have only one string.
+
+!llvm.commandline = !{!0, !1}
+!0 = !{!"commandline string"}
+!1 = !{!"string1", !"string2"}
+; CHECK: assembly parsed, but does not verify as correct!
+; CHECK-NEXT: incorrect number of operands in llvm.commandline metadata
+; CHECK-NEXT: !1
+
Index: test/Verifier/commandline-meta2.ll
===================================================================
--- /dev/null
+++ test/Verifier/commandline-meta2.ll
@@ -0,0 +1,13 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; Verify that llvm.commandline is properly structured.
+; llvm.commandline takes a list of metadata entries.
+; Each metadata entry can contain one string only.
+
+!llvm.commandline = !{!0, !1, !2, !3}
+!0 = !{!"str1"}
+!1 = !{!"str2"}
+!2 = !{!"str3"}
+!3 = !{i32 1}
+; CHECK: assembly parsed, but does not verify as correct!
+; CHECK-NEXT: invalid value for llvm.commandline metadata entry operand(the operand should be a string)
+; CHECK-NEXT: i32 1
Index: test/Verifier/commandline-meta3.ll
===================================================================
--- /dev/null
+++ test/Verifier/commandline-meta3.ll
@@ -0,0 +1,10 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; Verify that llvm.commandline is properly structured.
+; llvm.commandline takes a list of metadata entries.
+; Each metadata entry can contain one string only.
+
+!llvm.commandline = !{!0}
+!0 = !{!{!"nested metadata"}}
+; CHECK: assembly parsed, but does not verify as correct!
+; CHECK-NEXT: invalid value for llvm.commandline metadata entry operand(the operand should be a string)
+; CHECK-NEXT: !1
Index: test/Verifier/commandline-meta4.ll
===================================================================
--- /dev/null
+++ test/Verifier/commandline-meta4.ll
@@ -0,0 +1,9 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; Verify that llvm.commandline is properly structured.
+; llvm.commandline takes a list of metadata entries.
+; Each metadata entry can contain one string only.
+
+!llvm.commandline = !{!0}
+!0 = !{null}
+; CHECK: assembly parsed, but does not verify as correct!
+; CHECK-NEXT: invalid value for llvm.commandline metadata entry operand(the operand should be a string)