Index: include/lld/ReaderWriter/MachOLinkingContext.h
===================================================================
--- include/lld/ReaderWriter/MachOLinkingContext.h
+++ include/lld/ReaderWriter/MachOLinkingContext.h
@@ -79,6 +79,12 @@
   bool doNothing() const { return _doNothing; }
   bool printAtoms() const { return _printAtoms; }
 
+  ErrorOr<StringRef> searchPathForLibrary(StringRef path,
+                                          StringRef libName) const;
+
+  /// Searches directories for a match on the input File
+  ErrorOr<StringRef> searchLibrary(StringRef libName) const;
+
   /// \brief The dylib's binary compatibility version, in the raw uint32 format.
   ///
   /// When building a dynamic library, this is the compatibility version that
@@ -125,6 +131,8 @@
   }
   void setBundleLoader(StringRef loader) { _bundleLoader = loader; }
   void setPrintAtoms(bool value=true) { _printAtoms = value; }
+  void setSyslibRoot(StringRef path) { _syslibRoot = path; }
+
   StringRef dyldPath() const { return "/usr/lib/dyld"; }
 
   static Arch archFromCpuType(uint32_t cputype, uint32_t cpusubtype);
@@ -153,6 +161,7 @@
 
   static ArchInfo _s_archInfos[];
 
+  StringRef _syslibRoot;
   HeaderFileType _outputMachOType;   // e.g MH_EXECUTE
   bool _outputMachOTypeStatic; // Disambiguate static vs dynamic prog
   bool _doNothing;            // for -help and -v which just print info
Index: lib/Driver/DarwinLdDriver.cpp
===================================================================
--- lib/Driver/DarwinLdDriver.cpp
+++ lib/Driver/DarwinLdDriver.cpp
@@ -268,12 +268,31 @@
 
   std::unique_ptr<InputGraph> inputGraph(new InputGraph());
 
+  if (llvm::opt::Arg *syslibRoot = parsedArgs->getLastArg(OPT_syslibroot)) {
+    ctx.setSyslibRoot(syslibRoot->getValue());
+  }
+
   // Handle input files
-  for (llvm::opt::arg_iterator it = parsedArgs->filtered_begin(OPT_INPUT),
-                               ie = parsedArgs->filtered_end();
-                              it != ie; ++it) {
+  for (auto &arg : *parsedArgs) {
+    StringRef inputPath;
+    switch (arg->getOption().getID()) {
+    default:
+      continue;
+    case OPT_INPUT:
+      inputPath = arg->getValue();
+      break;
+    case OPT_l: {
+      ErrorOr<StringRef> resolvedPath = ctx.searchLibrary(arg->getValue());
+      if (!resolvedPath) {
+        diagnostics << "Unable to find library -l" << arg->getValue() << "\n";
+        return false;
+      }
+      inputPath = resolvedPath.get();
+      break;
+    }
+    }
     inputGraph->addInputElement(std::unique_ptr<InputElement>(
-        new MachOFileNode(ctx, (*it)->getValue(), globalWholeArchive)));
+        new MachOFileNode(ctx, inputPath, globalWholeArchive)));
   }
 
   if (!inputGraph->size()) {
Index: lib/Driver/DarwinLdOptions.td
===================================================================
--- lib/Driver/DarwinLdOptions.td
+++ lib/Driver/DarwinLdOptions.td
@@ -69,9 +69,16 @@
 def all_load : Flag<["-"], "all_load">,
         HelpText<"Forces all members of all static libraries to be loaded">,
         Group<grp_libs>;
+def syslibroot : Separate<["-"], "syslibroot">,
+        HelpText<"Add prefix to all system library search paths">,
+        Group<grp_libs>;
+
+// Input options
+def l : Joined<["-"], "l">,
+        HelpText<"Root name of library to searchf for">;
 
 // test case options
-def print_atoms : Flag<["-"], "print_atoms">, 
+def print_atoms : Flag<["-"], "print_atoms">,
         HelpText<"Emit output as yaml atoms">;
 
 // general options
Index: lib/ReaderWriter/MachO/MachOLinkingContext.cpp
===================================================================
--- lib/ReaderWriter/MachO/MachOLinkingContext.cpp
+++ lib/ReaderWriter/MachO/MachOLinkingContext.cpp
@@ -20,8 +20,10 @@
 
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MachO.h"
+#include "llvm/Support/Path.h"
 
 using lld::mach_o::KindHandler;
 using namespace llvm::MachO;
@@ -262,6 +264,49 @@
   }
 }
 
+ErrorOr<StringRef>
+MachOLinkingContext::searchPathForLibrary(StringRef path,
+                                          StringRef libName) const {
+  SmallString<128> fullPath;
+  if (libName.endswith(".o")) {
+    // A request ending in .o is special: just search for the file directly.
+    fullPath.assign(path);
+    llvm::sys::path::append(fullPath, libName);
+    if (llvm::sys::fs::exists(fullPath.str()))
+      return StringRef(*new (_allocator) std::string(fullPath.str()));
+    return make_error_code(llvm::errc::no_such_file_or_directory);
+  }
+
+  // Search for dynamic library
+  fullPath.assign(path);
+  llvm::sys::path::append(fullPath, Twine("lib") + libName + ".dylib");
+  if (llvm::sys::fs::exists(fullPath.str()))
+    return StringRef(*new (_allocator) std::string(fullPath.str()));
+
+  // If not, try for a static library
+  fullPath.assign(path);
+  llvm::sys::path::append(fullPath, Twine("lib") + libName + ".a");
+  if (llvm::sys::fs::exists(fullPath.str()))
+    return StringRef(*new (_allocator) std::string(fullPath.str()));
+
+  return make_error_code(llvm::errc::no_such_file_or_directory);
+}
+
+ErrorOr<StringRef> MachOLinkingContext::searchLibrary(StringRef libName) const {
+  SmallString<128> path;
+  static const char *syslibPaths[] = {"/usr/lib", "/usr/local/lib"};
+  for (StringRef dir : syslibPaths) {
+    path.assign(_syslibRoot);
+    llvm::sys::path::append(path, dir);
+
+    ErrorOr<StringRef> ec = searchPathForLibrary(path, libName);
+    if (ec)
+      return ec;
+  }
+
+  return make_error_code(llvm::errc::no_such_file_or_directory);
+}
+
 bool MachOLinkingContext::validateImpl(raw_ostream &diagnostics) {
   // TODO: if -arch not specified, look at arch of first .o file.
 
Index: test/mach-o/lib-search-paths.yaml
===================================================================
--- /dev/null
+++ test/mach-o/lib-search-paths.yaml
@@ -0,0 +1,16 @@
+# RUN: lld -flavor darwin -arch x86_64 %s -syslibroot %p/Inputs/lib-search-paths -lmyshared -lmystatic -lfile.o -print_atoms 2>&1 -r | FileCheck %s
+
+--- !native
+undefined-atoms:
+    - name: _from_myshared
+    - name: _from_mystatic
+    - name: _from_fileo
+
+# CHECK: defined-atoms:
+# CHECK:   - name:            _from_mystatic
+# CHECK:     content:         [ 02, 00, 00, 00 ]
+# CHECK:   - name:            _from_fileo
+# CHECK:     content:         [ 2A, 00, 00, 00 ]
+# CHECK: shared-library-atoms:
+# CHECK:   - name:            _from_myshared
+# CHECK:     load-name:       libmyshared.dylib