Index: llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
===================================================================
--- llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
+++ llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
@@ -191,7 +191,8 @@
   file_magic Magic = identify_magic(MB.getBuffer());
 
   if (Magic != file_magic::coff_object && Magic != file_magic::bitcode &&
-      Magic != file_magic::archive && Magic != file_magic::windows_resource) {
+      Magic != file_magic::archive && Magic != file_magic::windows_resource &&
+      Magic != file_magic::coff_import_library) {
     llvm::errs() << MB.getBufferIdentifier()
                  << ": not a COFF object, bitcode, archive or resource file\n";
     exit(1);
Index: llvm/test/tools/llvm-lib/implibs.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-lib/implibs.test
@@ -0,0 +1,12 @@
+Test that import libraries (and the members thereof) can be added to another
+static library.
+
+RUN: rm -rf %t
+RUN: mkdir -p %t
+
+RUN: echo -e "EXPORTS\nMyFunc" > %t/lib.def
+RUN: llvm-dlltool -m i386:x86-64 -l %t/lib.lib -d %t/lib.def -D lib.dll
+RUN: llvm-lib -out:%t/newlib.lib %t/lib.lib
+
+RUN: llvm-ar t %t/newlib.lib | FileCheck %s
+CHECK: lib.dll