Index: llvm/trunk/lib/ToolDrivers/llvm-lib/LibDriver.cpp
===================================================================
--- llvm/trunk/lib/ToolDrivers/llvm-lib/LibDriver.cpp
+++ llvm/trunk/lib/ToolDrivers/llvm-lib/LibDriver.cpp
@@ -96,6 +96,47 @@
   return "";
 }
 
+static void fatalOpenError(llvm::Error E, Twine File) {
+  if (!E)
+    return;
+  handleAllErrors(std::move(E), [&](const llvm::ErrorInfoBase &EIB) {
+    llvm::errs() << "error opening '" << File << "': " << EIB.message() << '\n';
+    exit(1);
+  });
+}
+
+static void doList(opt::InputArgList& Args) {
+  // lib.exe prints the contents of the first archive file.
+  std::unique_ptr<MemoryBuffer> B;
+  for (auto *Arg : Args.filtered(OPT_INPUT)) {
+    // Create or open the archive object.
+    ErrorOr<std::unique_ptr<MemoryBuffer>> MaybeBuf =
+        MemoryBuffer::getFile(Arg->getValue(), -1, false);
+    fatalOpenError(errorCodeToError(MaybeBuf.getError()), Arg->getValue());
+
+    if (identify_magic(MaybeBuf.get()->getBuffer()) == file_magic::archive) {
+      B = std::move(MaybeBuf.get());
+      break;
+    }
+  }
+
+  // lib.exe doesn't print an error if no .lib files are passed.
+  if (!B)
+    return;
+
+  Error Err = Error::success();
+  object::Archive Archive(B.get()->getMemBufferRef(), Err);
+  fatalOpenError(std::move(Err), B->getBufferIdentifier());
+
+  for (auto &C : Archive.children(Err)) {
+    Expected<StringRef> NameOrErr = C.getName();
+    fatalOpenError(NameOrErr.takeError(), B->getBufferIdentifier());
+    StringRef Name = NameOrErr.get();
+    llvm::outs() << Name << '\n';
+  }
+  fatalOpenError(std::move(Err), B->getBufferIdentifier());
+}
+
 int llvm::libDriverMain(ArrayRef<const char *> ArgsArr) {
   BumpPtrAllocator Alloc;
   StringSaver Saver(Alloc);
@@ -130,6 +171,11 @@
   if (!Args.hasArgNoClaim(OPT_INPUT))
     return 0;
 
+  if (Args.hasArg(OPT_lst)) {
+    doList(Args);
+    return 0;
+  }
+
   std::vector<StringRef> SearchPaths = getSearchPaths(&Args, Saver);
 
   // Create a NewArchiveMember for each input file.
Index: llvm/trunk/lib/ToolDrivers/llvm-lib/Options.td
===================================================================
--- llvm/trunk/lib/ToolDrivers/llvm-lib/Options.td
+++ llvm/trunk/lib/ToolDrivers/llvm-lib/Options.td
@@ -10,6 +10,9 @@
       Joined<["/", "-", "-?"], name#":">, HelpText<help>;
 
 def libpath: P<"libpath", "Object file search path">;
+
+// Can't be called "list" since that's a keyword.
+def lst    : F<"list">, HelpText<"List contents of .lib file on stdout">;
 def out    : P<"out", "Path to file to write output">;
 
 def llvmlibthin : F<"llvmlibthin">,
Index: llvm/trunk/test/tools/llvm-lib/list.test
===================================================================
--- llvm/trunk/test/tools/llvm-lib/list.test
+++ llvm/trunk/test/tools/llvm-lib/list.test
@@ -0,0 +1,14 @@
+RUN: rm -rf %t && mkdir -p %t
+RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o %t/a.obj %S/Inputs/a.s
+RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o %t/b.obj %S/Inputs/b.s
+
+RUN: rm -f %t/l.lib
+RUN: llvm-lib /out:%t/foo.lib %t/a.obj %t/b.obj
+
+# This should ignore the two .obj files, then print the first .lib file,
+# then ignore the 2nd one.
+RUN: llvm-lib /list %t/a.obj %t/b.obj %t/foo.lib %t/foo.lib | FileCheck %s
+
+CHECK: a.obj
+CHECK: b.obj
+CHECK-NOT: a.obj