diff --git a/lib/SILOptimizer/PassManager/PassPipeline.cpp b/lib/SILOptimizer/PassManager/PassPipeline.cpp
index 1b5025681b067..d0ce247eea2bf 100644
--- a/lib/SILOptimizer/PassManager/PassPipeline.cpp
+++ b/lib/SILOptimizer/PassManager/PassPipeline.cpp
@@ -527,7 +527,7 @@ void addFunctionPasses(SILPassPipelinePlan &P,
   // of embedded Swift.
   if (!P.getOptions().EmbeddedSwift) {
     P.addGenericSpecializer();
-    P.addPackSpecialization();
+    // P.addPackSpecialization();
     // Run devirtualizer after the specializer, because many
     // class_method/witness_method instructions may use concrete types now.
     P.addDevirtualizer();
diff --git a/test/SILOptimizer/pack_specialization.swift b/test/SILOptimizer/pack_specialization.swift
index 770bc19199b37..db3437040302e 100644
--- a/test/SILOptimizer/pack_specialization.swift
+++ b/test/SILOptimizer/pack_specialization.swift
@@ -1,3 +1,4 @@
+// XFAIL: *
 // RUN: %target-swift-frontend %s -emit-ir -O | %FileCheck %s
 
 // REQUIRES: swift_in_compiler