diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -597,32 +597,44 @@
     return !errorCount();
   }
 
+  DenseSet<StringRef> weakImportPaths;
+
   for (const auto &arg : args) {
     const auto &opt = arg->getOption();
     warnIfDeprecatedOption(opt);
-    switch (arg->getOption().getID()) {
+    switch (opt.getID()) {
     case OPT_INPUT:
       addFile(arg->getValue());
       break;
+    case OPT_weak_library:
+      addFile(arg->getValue());
+      weakImportPaths.insert(arg->getValue());
+      break;
     case OPT_filelist:
       addFileList(arg->getValue());
       break;
     case OPT_force_load:
       forceLoadArchive(arg->getValue());
       break;
-    case OPT_l: {
+    case OPT_l:
+    case OPT_weak_l: {
       StringRef name = arg->getValue();
       if (Optional<std::string> path = findLibrary(name)) {
         addFile(*path);
+        if (opt.getID() == OPT_weak_l)
+          weakImportPaths.insert(saver.save(*path));
         break;
       }
       error("library not found for -l" + name);
       break;
     }
-    case OPT_framework: {
+    case OPT_framework:
+    case OPT_weak_framework: {
       StringRef name = arg->getValue();
       if (Optional<std::string> path = findFramework(name)) {
         addFile(*path);
+        if (opt.getID() == OPT_weak_framework)
+          weakImportPaths.insert(saver.save(*path));
         break;
       }
       error("framework not found for -framework " + name);
@@ -661,6 +673,11 @@
                   config->outputType == MH_BUNDLE ||
                   (config->outputType == MH_EXECUTE && args.hasArg(OPT_pie));
 
+  for (InputFile *file : inputFiles)
+    if (auto *dylibFile = dyn_cast<DylibFile>(file))
+      if (weakImportPaths.contains(file->getName()))
+        dylibFile->forceWeakImport = true;
+
   // Now that all dylibs have been loaded, search for those that should be
   // re-exported.
   for (opt::Arg *arg : args.filtered(OPT_sub_library)) {
diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h
--- a/lld/MachO/InputFiles.h
+++ b/lld/MachO/InputFiles.h
@@ -109,6 +109,7 @@
   StringRef dylibName;
   uint64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel
   bool reexport = false;
+  bool forceWeakImport = false;
   std::vector<DylibFile *> reexported;
 };
 
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -65,12 +65,10 @@
 def weak_l : Joined<["-"], "weak-l">,
      MetaVarName<"<name>">,
      HelpText<"Like -l<name>, but mark library and its references as weak imports">,
-     Flags<[HelpHidden]>,
      Group<grp_libs>;
 def weak_library : Separate<["-"], "weak_library">,
      MetaVarName<"<path>">,
      HelpText<"Like bare <path>, but mark library and its references as weak imports">,
-     Flags<[HelpHidden]>,
      Group<grp_libs>;
 def reexport_l : Joined<["-"], "reexport-l">,
      MetaVarName<"<name>">,
@@ -120,7 +118,6 @@
 def weak_framework : Separate<["-"], "weak_framework">,
      MetaVarName<"<name>">,
      HelpText<"Like -framework <name>, but mark framework and its references as weak imports">,
-     Flags<[HelpHidden]>,
      Group<grp_libs>;
 def reexport_framework : Separate<["-"], "reexport_framework">,
      MetaVarName<"<name>">,
diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -385,8 +385,11 @@
   uint64_t dylibOrdinal = 1;
   for (InputFile *file : inputFiles) {
     if (auto *dylibFile = dyn_cast<DylibFile>(file)) {
-      in.header->addLoadCommand(
-          make<LCDylib>(LC_LOAD_DYLIB, dylibFile->dylibName));
+      // TODO: dylibs that are only referenced by weak refs should also be
+      // loaded via LC_LOAD_WEAK_DYLIB.
+      LoadCommandType lcType =
+          dylibFile->forceWeakImport ? LC_LOAD_WEAK_DYLIB : LC_LOAD_DYLIB;
+      in.header->addLoadCommand(make<LCDylib>(lcType, dylibFile->dylibName));
       dylibFile->ordinal = dylibOrdinal++;
 
       if (dylibFile->reexport)
diff --git a/lld/test/MachO/weak-import.s b/lld/test/MachO/weak-import.s
new file mode 100644
--- /dev/null
+++ b/lld/test/MachO/weak-import.s
@@ -0,0 +1,31 @@
+# REQUIRES: x86
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo.s -o %t/foo.o
+# RUN: lld -flavor darwinnew -syslibroot %S/Inputs/MacOSX.sdk -lSystem -dylib %t/foo.o -o %t/libfoo.dylib
+
+# RUN: lld -flavor darwinnew -syslibroot %S/Inputs/MacOSX.sdk -weak-lSystem %t/test.o -weak_framework CoreFoundation -weak_library %t/libfoo.dylib -o %t/test
+# RUN: llvm-objdump --macho --all-headers %t/test | FileCheck %s -DDIR=%t
+
+# CHECK:          cmd LC_LOAD_WEAK_DYLIB
+# CHECK-NEXT: cmdsize
+# CHECK-NEXT:    name /usr/lib/libSystem.B.dylib
+
+# CHECK:          cmd LC_LOAD_WEAK_DYLIB
+# CHECK-NEXT: cmdsize
+# CHECK-NEXT:    name /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
+
+# CHECK:          cmd LC_LOAD_WEAK_DYLIB
+# CHECK-NEXT: cmdsize
+# CHECK-NEXT:    name [[DIR]]/libfoo.dylib
+
+#--- foo.s
+.globl _foo
+_foo:
+  ret
+
+#--- test.s
+.globl _main
+.text
+_main:
+  ret