diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -188,6 +188,8 @@
   SymbolPatterns unexportedSymbols;
   SymbolPatterns whyLive;
 
+  llvm::DenseMap<llvm::StringRef, llvm::StringRef> aliasedSymbols;
+
   SymtabPresence localSymbolsPresence = SymtabPresence::All;
   SymbolPatterns localSymbolPatterns;
 
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -1306,6 +1306,10 @@
       OPT_call_graph_profile_sort, OPT_no_call_graph_profile_sort, true);
   config->printSymbolOrder = args.getLastArgValue(OPT_print_symbol_order);
 
+  for (const Arg *arg : args.filtered(OPT_alias)) {
+    config->aliasedSymbols[arg->getValue(0)] = arg->getValue(1);
+  }
+
   // FIXME: Add a commandline flag for this too.
   config->zeroModTime = getenv("ZERO_AR_DATE");
 
@@ -1558,6 +1562,22 @@
     createSyntheticSections();
     createSyntheticSymbols();
 
+    for (auto pair : config->aliasedSymbols) {
+      if (auto *sym = symtab->find(pair.getFirst())) {
+        if (auto *defined = dyn_cast<Defined>(sym)) {
+          symtab->addDefined(pair.getSecond(), defined->getFile(),
+                             defined->isec, defined->value, defined->size,
+                             defined->isWeakDef(), defined->privateExtern,
+                             defined->thumb, defined->referencedDynamically,
+                             defined->noDeadStrip, defined->weakDefCanBeHidden);
+          continue;
+        }
+      }
+
+      warn("undefined base symbol '" + pair.getFirst() + "' for alias '" +
+           pair.getSecond() + "'\n");
+    }
+
     if (config->hasExplicitExports) {
       parallelForEach(symtab->getSymbols(), [](Symbol *sym) {
         if (auto *defined = dyn_cast<Defined>(sym)) {
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -505,7 +505,6 @@
 def alias : MultiArg<["-"], "alias", 2>,
     MetaVarName<"<symbol_name> <alternate_name>">,
     HelpText<"Create a symbol alias with default global visibility">,
-    Flags<[HelpHidden]>,
     Group<grp_resolve>;
 def alias_list : Separate<["-"], "alias_list">,
     MetaVarName<"<file>">,
diff --git a/lld/test/MachO/aliases.s b/lld/test/MachO/aliases.s
new file mode 100644
--- /dev/null
+++ b/lld/test/MachO/aliases.s
@@ -0,0 +1,45 @@
+# REQUIRES: x86
+# RUN: rm -rf %t; split-file %s %t
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos -o %t/foo.o %t/foo.s
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos -o %t/main.o %t/main.s
+
+# RUN: not %lld -alias 2>&1 | FileCheck %s --check-prefix=INVALIDARG
+# RUN: not %lld -alias missing_second 2>&1 | FileCheck %s --check-prefix=INVALIDARG
+
+# INVALIDARG: error: -alias: missing argument
+
+# RUN: %lld -alias _foo _bar -u _bar -exported_symbol _bar %t/main.o %t/foo.o -o %t/bar.o
+# RUN: llvm-nm %t/bar.o | FileCheck %s --check-prefix=BAR
+
+# BAR: _bar
+# BAR: _foo
+
+# RUN: not %lld -alias _missing _bar -alias _missing2 _baz %t/main.o -o %t/missing.o %s 2>&1 | FileCheck %s --check-prefix=MISSING
+
+# MISSING-DAG: undefined base symbol '_missing' for alias '_bar'
+# MISSING-DAG: undefined base symbol '_missing2' for alias '_baz'
+
+# RUN: %lld -alias _foo _main %t/foo.o -o %t/main_rename.o
+# RUN: llvm-nm %t/main_rename.o | FileCheck %s --check-prefix=MAIN
+
+# MAIN: _foo
+# MAIN: _main
+
+# RUN: %lld -alias _foo _bar -alias _main _fake_main %t/main.o %t/foo.o -o %t/multiple.o
+# RUN: llvm-nm %t/multiple.o | FileCheck %s --check-prefix=MULTIPLE
+
+# MULTIPLE: _bar
+# MULTIPLE: _fake_main
+# MULTIPLE: _foo
+# MULTIPLE: _main
+
+#--- foo.s
+.globl _foo
+_foo:
+  ret
+
+#--- main.s
+.globl _main
+_main:
+  ret