diff --git a/driver/ir2obj_cache.cpp b/driver/ir2obj_cache.cpp
index 3949bbaa2d..a84f4de6ac 100644
--- a/driver/ir2obj_cache.cpp
+++ b/driver/ir2obj_cache.cpp
@@ -183,6 +183,9 @@ void outputIR2ObjRelevantCmdlineArgs(llvm::raw_ostream &hash_os)
       // All  "-ir2..." options can be ignored
       if (arg[1] == 'i' && arg[2] == 'r' && arg[3] == '2')
         continue;
+      // Ignore "-lib"
+      if (arg[1] == 'l' && arg[2] == 'i' && arg[3] == 'b' && !arg[4])
+        continue;
       // All effects of -d-version... are already included in the IR hash.
       if (strncmp(arg+1, "d-version", 9) == 0)
         continue;
diff --git a/tests/linking/ir2obj_caching_flags1.d b/tests/linking/ir2obj_caching_flags1.d
index 4db51c54d6..06022fb340 100644
--- a/tests/linking/ir2obj_caching_flags1.d
+++ b/tests/linking/ir2obj_caching_flags1.d
@@ -29,6 +29,7 @@
 // RUN:   && %ldc %s -c -of=%t%obj -ir2obj-cache=%T/flag1cache -D -H -I. -J.                    -vv | FileCheck --check-prefix=MUST_HIT %s \
 // RUN:   && %ldc %s -c -of=%t%obj -ir2obj-cache=%T/flag1cache -d-version=Irrelevant            -vv | FileCheck --check-prefix=MUST_HIT %s \
 // RUN:   && %ldc %s -c -of=%t%obj -ir2obj-cache=%T/flag1cache -unittest                        -vv | FileCheck --check-prefix=MUST_HIT %s \
+// RUN:   && %ldc %s               -ir2obj-cache=%T/flag1cache -lib                             -vv | FileCheck --check-prefix=MUST_HIT %s \
 // RUN:   && %ldc                  -ir2obj-cache=%T/flag1cache -vv -run %s                          | FileCheck --check-prefix=COULD_HIT %s \
 // RUN:   && %ldc                  -ir2obj-cache=%T/flag1cache -vv -run %s a b                      | FileCheck --check-prefix=MUST_HIT %s \
 // RUN:   && %ldc %s -c -of=%t%obj -ir2obj-cache=%T/flag1cache -g                               -vv | FileCheck --check-prefix=MUST_HIT %s