diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
index 7539481abbe45..83227a30d6a9a 100644
--- a/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
+++ b/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
@@ -584,6 +584,8 @@ void SILCombiner::buildConcreteOpenedExistentialInfos(
       // BuilderContext before rewriting any uses of the ConcreteType.
       OpenedArchetypesTracker.addOpenedArchetypeDef(
           cast<ArchetypeType>(CEI.ConcreteType), CEI.ConcreteTypeDef);
+    } else if (auto *I = CEI.ConcreteValue->getDefiningInstruction()) {
+      OpenedArchetypesTracker.registerUsedOpenedArchetypes(I);
     }
   }
 }
diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
index 743e4a83d0b5a..4b74af088ee2e 100644
--- a/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
+++ b/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
@@ -480,7 +480,8 @@ SILInstruction *SILCombiner::visitAllocStackInst(AllocStackInst *AS) {
   // Be careful with open archetypes, because they cannot be moved before
   // their definitions.
   if (IEI && !OEI &&
-      !IEI->getLoweredConcreteType().isOpenedExistential()) {
+      !IEI->getLoweredConcreteType().hasOpenedExistential()) {
+    assert(!IEI->getLoweredConcreteType().isOpenedExistential());
     auto *ConcAlloc = Builder.createAllocStack(
         AS->getLoc(), IEI->getLoweredConcreteType(), AS->getVarInfo());
     IEI->replaceAllUsesWith(ConcAlloc);
diff --git a/test/SILOptimizer/sil_combine.sil b/test/SILOptimizer/sil_combine.sil
index 0b28ba548b130..ab9ca8c989b75 100644
--- a/test/SILOptimizer/sil_combine.sil
+++ b/test/SILOptimizer/sil_combine.sil
@@ -3189,6 +3189,33 @@ bb0(%0 : $VV):
   return %26 : $()
 }
 
+sil @any_to_object : $@convention(thin) <τ_0_0> (@in_guaranteed τ_0_0) -> @owned AnyObject
+
+// CHECK-LABEL: sil @dont_crash_when_propagating_existentials
+// CHECK:   [[EM:%[0-9]+]] = init_existential_metatype %0
+// CHECK:   [[S:%[0-9]+]] = alloc_stack $Any
+// CHECK:   [[M:%[0-9]+]] = open_existential_metatype [[EM]]
+// CHECK:   [[E:%[0-9]+]] = init_existential_addr [[S]]
+// CHECK:   store [[M]] to [[E]]
+// CHECK:   apply {{%[0-9]+}}<(@opened("5F99B72C-EC40-11EA-9534-8C8590A6A134") AnyObject).Type>([[E]])
+// CHECK: } // end sil function 'dont_crash_when_propagating_existentials'
+sil @dont_crash_when_propagating_existentials : $@convention(thin) () -> @owned AnyObject {
+bb0:
+  %0 = metatype $@thick C.Type
+  %1 = init_existential_metatype %0 : $@thick C.Type, $@thick AnyObject.Type
+  %3 = alloc_stack $Any, let, name "object"
+  %4 = open_existential_metatype %1 : $@thick AnyObject.Type to $@thick (@opened("5F99B72C-EC40-11EA-9534-8C8590A6A134") AnyObject).Type
+  %5 = init_existential_addr %3 : $*Any, $(@opened("5F99B72C-EC40-11EA-9534-8C8590A6A134") AnyObject).Type
+  store %4 to %5 : $*@thick (@opened("5F99B72C-EC40-11EA-9534-8C8590A6A134") AnyObject).Type
+  %7 = open_existential_addr immutable_access %3 : $*Any to $*@opened("5F9F1B04-EC40-11EA-9534-8C8590A6A134") Any
+  %8 = function_ref @any_to_object : $@convention(thin) <τ_0_0> (@in_guaranteed τ_0_0) -> @owned AnyObject
+  %9 = apply %8<@opened("5F9F1B04-EC40-11EA-9534-8C8590A6A134") Any>(%7) : $@convention(thin) <τ_0_0> (@in_guaranteed τ_0_0) -> @owned AnyObject
+  destroy_addr %3 : $*Any
+  dealloc_stack %3 : $*Any
+  return %9 : $AnyObject
+}
+
+
 // CHECK-LABEL: sil @remove_unused_alloc_ref
 // CHECK-NEXT: bb0
 // CHECK-NEXT: %0 = tuple ()