diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -235,6 +235,8 @@
   return v;
 }
 
+static DenseMap<StringRef, ArchiveFile *> loadedArchives;
+
 static InputFile *addFile(StringRef path, bool forceLoadArchive,
                           bool isExplicit = true,
                           bool isBundleLoader = false) {
@@ -247,6 +249,13 @@
   file_magic magic = identify_magic(mbref.getBuffer());
   switch (magic) {
   case file_magic::archive: {
+    // Avoid loading archives twice. If the archives are being force-loaded,
+    // loading them twice would create duplicate symbol errors. In the
+    // non-force-loading case, this is just a minor performance optimization.
+    ArchiveFile *&cachedFile = loadedArchives[path];
+    if (cachedFile)
+      return cachedFile;
+
     std::unique_ptr<object::Archive> file = CHECK(
         object::Archive::create(mbref), path + ": failed to parse archive");
 
@@ -286,7 +295,7 @@
       }
     }
 
-    newFile = make<ArchiveFile>(std::move(file));
+    newFile = cachedFile = make<ArchiveFile>(std::move(file));
     break;
   }
   case file_magic::macho_object:
diff --git a/lld/test/MachO/force-load.s b/lld/test/MachO/force-load.s
--- a/lld/test/MachO/force-load.s
+++ b/lld/test/MachO/force-load.s
@@ -5,19 +5,40 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo.s -o %t/foo.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o
 
-# RUN: %lld -force_load %t/foo.a %t/foo.o %t/test.o -o %t/test-force-load-first
+# RUN: %lld -lSystem -force_load %t/foo.a %t/foo.o %t/test.o -o %t/test-force-load-first
 # FORCE-LOAD-FIRST:  __TEXT,archive _foo
 # RUN: llvm-objdump --syms %t/test-force-load-first | FileCheck %s --check-prefix=FORCE-LOAD-FIRST
 
-# RUN: %lld %t/foo.o -force_load %t/foo.a %t/test.o -o %t/test-force-load-second
+# RUN: %lld %t/foo.o -lSystem -force_load %t/foo.a %t/test.o -o %t/test-force-load-second
 # RUN: llvm-objdump --syms %t/test-force-load-second | FileCheck %s --check-prefix=FORCE-LOAD-SECOND
 # FORCE-LOAD-SECOND: __TEXT,obj _foo
 
+## Force-loading the same path twice is fine
+# RUN: %lld -lSystem %t/foo.o -force_load %t/foo.a -force_load %t/foo.a %t/test.o -o /dev/null
+
+## Note that we do not call realpath() before dedup'ing the force-load
+## arguments, so this is an error.
+# RUN: cd %t; not %lld -lSystem %t/foo.o -force_load %t/foo.a -force_load foo.a \
+# RUN:   %t/test.o -o /dev/null 2>&1
+
+## XXX not sure this is worth committing, but it demonstrates that we treat
+## symlinks and hardlinks as distinct inputs too.
+# RUN: ln -s %t/foo.a %t/bar.a
+# RUN: not %lld -lSystem %t/foo.o -force_load %t/foo.a -force_load %t/bar.a \
+# RUN:   %t/test.o -o /dev/null 2>&1
+
+# RUN: ln %t/foo.a %t/baz.a
+# RUN: not %lld -lSystem %t/foo.o -force_load %t/foo.a -force_load %t/baz.a \
+# RUN:   %t/test.o -o /dev/null 2>&1
+
+# DUP: error: duplicate symbol: _bar
+
 #--- archive-foo.s
 .section __TEXT,archive
-.globl _foo
+.globl _foo, _bar
 .weak_definition _foo
 _foo:
+_bar:
 
 #--- foo.s
 .section __TEXT,obj