diff --git a/docs/SIL.rst b/docs/SIL.rst
index a941ec7b86b..e6442bb9b5c 100644
--- a/docs/SIL.rst
+++ b/docs/SIL.rst
@@ -1624,18 +1624,6 @@ TODO: ``builtin_zero`` is a temporary hack to support our current AST-level
 default initialization implementation. Definitive assignment analysis in SIL
 will supersede this.
 
-module
-``````
-::
-
-  sil-instruction ::= 'module' sil-decl-ref
-
-  %1 = module #M
-  // #M must be a module name
-  // %1 has type $module<M>
-
-Creates a module value for the module ``M``.
-
 Dynamic Dispatch
 ~~~~~~~~~~~~~~~~
 
diff --git a/include/swift/SIL/SILBuilder.h b/include/swift/SIL/SILBuilder.h
index 5139e74c085..e1d73cf41e7 100644
--- a/include/swift/SIL/SILBuilder.h
+++ b/include/swift/SIL/SILBuilder.h
@@ -594,10 +594,6 @@ public:
     return insert(new (F.getModule()) ProtocolMetatypeInst(Loc, Metatype,Base));
   }
   
-  ModuleInst *createModule(SILLocation Loc, SILType ModuleType) {
-    return insert(new (F.getModule()) ModuleInst(Loc, ModuleType));
-  }
-  
   StrongRetainInst *createStrongRetain(SILLocation Loc, SILValue Operand) {
     return insert(new (F.getModule()) StrongRetainInst(Loc, Operand));
   }
diff --git a/include/swift/SIL/SILCloner.h b/include/swift/SIL/SILCloner.h
index 9c851b640e4..4b5986bc5d9 100644
--- a/include/swift/SIL/SILCloner.h
+++ b/include/swift/SIL/SILCloner.h
@@ -621,14 +621,6 @@ SILCloner<ImplClass>::visitProtocolMetatypeInst(ProtocolMetatypeInst *Inst) {
                                    getOpValue(Inst->getOperand())));
 }
 
-template<typename ImplClass>
-void
-SILCloner<ImplClass>::visitModuleInst(ModuleInst *Inst) {
-  doPostProcess(Inst,
-    Builder.createModule(getOpLocation(Inst->getLoc()),
-                         getOpType(Inst->getType())));
-}
-
 template<typename ImplClass>
 void
 SILCloner<ImplClass>::visitTupleExtractInst(TupleExtractInst *Inst) {
diff --git a/include/swift/SIL/SILInstruction.h b/include/swift/SIL/SILInstruction.h
index d726063acb7..7c15528ba1b 100644
--- a/include/swift/SIL/SILInstruction.h
+++ b/include/swift/SIL/SILInstruction.h
@@ -1344,23 +1344,6 @@ public:
     : UnaryInstructionBase(Loc, Base, Metatype) {}
 };
 
-/// ModuleInst - Represents a reference to a module as a value.
-class ModuleInst : public SILInstruction {
-public:
-  
-  ModuleInst(SILLocation Loc, SILType ModuleType);
-  
-  /// getType() is ok since this is known to only have one type.
-  SILType getType(unsigned i = 0) const { return ValueBase::getType(i); }
-
-  ArrayRef<Operand> getAllOperands() const { return {}; }
-  MutableArrayRef<Operand> getAllOperands() { return {}; }
-
-  static bool classof(const ValueBase *V) {
-    return V->getKind() == ValueKind::ModuleInst;
-  }
-};
-  
 /// Extract a numbered element out of a value of tuple type.
 class TupleExtractInst
   : public UnaryInstructionBase<ValueKind::TupleExtractInst>
diff --git a/include/swift/SIL/SILNodes.def b/include/swift/SIL/SILNodes.def
index 17e3ad693ba..25830f98cf7 100644
--- a/include/swift/SIL/SILNodes.def
+++ b/include/swift/SIL/SILNodes.def
@@ -106,7 +106,6 @@ ABSTRACT_VALUE(SILInstruction, ValueBase)
   INST(FloatLiteralInst, SILInstruction, None)
   INST(StringLiteralInst, SILInstruction, None)
   INST(BuiltinZeroInst, SILInstruction, None)
-  INST(ModuleInst, SILInstruction, None)
 
   // Dynamic Dispatch
   ABSTRACT_VALUE(MethodInst, SILInstruction)
diff --git a/lib/IRGen/IRGenSIL.cpp b/lib/IRGen/IRGenSIL.cpp
index ac5f7752a20..d3582b21a2c 100644
--- a/lib/IRGen/IRGenSIL.cpp
+++ b/lib/IRGen/IRGenSIL.cpp
@@ -539,7 +539,6 @@ public:
   void visitStructExtractInst(StructExtractInst *i);
   void visitStructElementAddrInst(StructElementAddrInst *i);
   void visitRefElementAddrInst(RefElementAddrInst *i);
-  void visitModuleInst(ModuleInst *i);
 
   void visitClassMethodInst(ClassMethodInst *i);
   void visitSuperMethodInst(SuperMethodInst *i);
@@ -2044,12 +2043,6 @@ void IRGenSILFunction::visitRefElementAddrInst(swift::RefElementAddrInst *i) {
   setLoweredAddress(SILValue(i, 0), field);
 }
 
-void IRGenSILFunction::visitModuleInst(swift::ModuleInst *i) {
-  // Currently, module values are always empty.
-  Explosion empty(ExplosionKind::Maximal);
-  setLoweredExplosion(SILValue(i, 0), empty);
-}
-
 void IRGenSILFunction::visitLoadInst(swift::LoadInst *i) {
   Explosion lowered(ExplosionKind::Maximal);
   Address source = getLoweredAddress(i->getOperand());
diff --git a/lib/Parse/ParseSIL.cpp b/lib/Parse/ParseSIL.cpp
index 2803c1c89e4..fa694e87c09 100644
--- a/lib/Parse/ParseSIL.cpp
+++ b/lib/Parse/ParseSIL.cpp
@@ -923,7 +923,6 @@ bool SILParser::parseSILOpcode(ValueKind &Opcode, SourceLoc &OpcodeLoc,
     .Case("mark_uninitialized", ValueKind::MarkUninitializedInst)
     .Case("mark_function_escape", ValueKind::MarkFunctionEscapeInst)
     .Case("metatype", ValueKind::MetatypeInst)
-    .Case("module", ValueKind::ModuleInst)
     .Case("object_pointer_to_ref", ValueKind::ObjectPointerToRefInst)
     .Case("partial_apply", ValueKind::PartialApplyInst)
     .Case("pointer_to_address", ValueKind::PointerToAddressInst)
@@ -2100,21 +2099,6 @@ bool SILParser::parseSILInstruction(SILBasicBlock *BB) {
                   ArrayRef<ProtocolConformance*>());
     break;
   }
-  case ValueKind::ModuleInst: {
-    Identifier ModuleName;
-    SourceLoc ModuleLoc;
-    // Parse reference to a module.
-    if (P.parseToken(tok::sil_pound, diag::expected_sil_constant) ||
-        parseSILIdentifier(ModuleName, ModuleLoc, diag::expected_sil_constant))
-      return true;
-    llvm::PointerUnion<ValueDecl*, Module *> Res = lookupTopDecl(P, ModuleName);
-    assert(Res.is<Module*>() && "Expect a module name in ModuleInst");
-    auto Mod = Res.get<Module*>();
-    ResultVal = B.createModule(InstLoc,
-                  SILType::getPrimitiveObjectType(
-                    ModuleType::get(Mod)->getCanonicalType()));
-    break;
-  }
   case ValueKind::DynamicMethodBranchInst: {
     SILDeclRef Member;
     Identifier BBName, BBName2;
diff --git a/lib/SIL/SILInstruction.cpp b/lib/SIL/SILInstruction.cpp
index 464f99a0729..c1b7cc0b1dd 100644
--- a/lib/SIL/SILInstruction.cpp
+++ b/lib/SIL/SILInstruction.cpp
@@ -550,9 +550,6 @@ TupleInst::TupleInst(SILLocation Loc, SILType Ty, ArrayRef<SILValue> Elems)
 MetatypeInst::MetatypeInst(SILLocation Loc, SILType Metatype)
   : SILInstruction(ValueKind::MetatypeInst, Loc, Metatype) {}
 
-ModuleInst::ModuleInst(SILLocation Loc, SILType ModuleType)
-  : SILInstruction(ValueKind::ModuleInst, Loc, ModuleType) {}
-
 ProjectExistentialInst::ProjectExistentialInst(SILLocation Loc,
                                                SILValue Operand,
                                                SILType SelfTy)
diff --git a/lib/SIL/SILPrinter.cpp b/lib/SIL/SILPrinter.cpp
index 5d9d9a51975..7a7f69f434f 100644
--- a/lib/SIL/SILPrinter.cpp
+++ b/lib/SIL/SILPrinter.cpp
@@ -893,9 +893,6 @@ public:
   void visitMetatypeInst(MetatypeInst *MI) {
     OS << "metatype " << MI->getType();
   }
-  void visitModuleInst(ModuleInst *MI) {
-    OS << "module #" << MI->getType().castTo<ModuleType>()->getModule()->Name;
-  }
   
   void visitStrongRetainInst(StrongRetainInst *RI) {
     OS << "strong_retain " << getIDAndType(RI->getOperand());
diff --git a/lib/SIL/Verifier.cpp b/lib/SIL/Verifier.cpp
index dfb0780723c..654ded4f1fa 100644
--- a/lib/SIL/Verifier.cpp
+++ b/lib/SIL/Verifier.cpp
@@ -586,10 +586,6 @@ public:
             CanType(MI->getType().castTo<MetaTypeType>()->getInstanceType()),
             "protocol_metatype result must be metatype of operand type");
   }
-  void checkModuleInst(ModuleInst *MI) {
-    require(MI->getType(0).is<ModuleType>(),
-            "module instruction must be of module type");
-  }
   
   void checkStrongRetainInst(StrongRetainInst *RI) {
     requireReferenceValue(RI->getOperand(), "Operand of strong_retain");
diff --git a/lib/SILGen/SILGenExpr.cpp b/lib/SILGen/SILGenExpr.cpp
index 7bc92a9852d..7b9e546de1d 100644
--- a/lib/SILGen/SILGenExpr.cpp
+++ b/lib/SILGen/SILGenExpr.cpp
@@ -20,6 +20,7 @@
 #include "swift/Basic/SourceManager.h"
 #include "swift/Basic/type_traits.h"
 #include "swift/SIL/SILArgument.h"
+#include "swift/SIL/SILUndef.h"
 #include "swift/SIL/TypeLowering.h"
 #include "Initialization.h"
 #include "LValue.h"
@@ -1167,8 +1168,9 @@ RValue RValueEmitter::visitDotSyntaxBaseIgnoredExpr(
 }
 
 RValue RValueEmitter::visitModuleExpr(ModuleExpr *E, SGFContext C) {
-  SILValue module =
-    SGF.B.createModule(E, SGF.getLoweredLoadableType(E->getType()));
+  // Produce an undef value. The module value should never actually be used.
+  SILValue module = SILUndef::get(SGF.getLoweredLoadableType(E->getType()),
+                                  SGF.SGM.M);
   return RValue(SGF, ManagedValue(module, ManagedValue::Unmanaged), E);
 }
 
diff --git a/lib/Serialization/DeserializeSIL.cpp b/lib/Serialization/DeserializeSIL.cpp
index e91f04c8ba7..1232f9e94f7 100644
--- a/lib/Serialization/DeserializeSIL.cpp
+++ b/lib/Serialization/DeserializeSIL.cpp
@@ -748,13 +748,6 @@ bool SILDeserializer::readSILInstruction(SILFunction *Fn, SILBasicBlock *BB,
     ResultVal = Builder.createMarkFunctionEscape(Loc, OpList);
     break;
   }
-  case ValueKind::ModuleInst: {
-    // Has IdentifierID for the module reference. Use SILOneTypeLayout.
-    auto Mod = MF->getModule(MF->getIdentifier(TyID));
-    ResultVal = Builder.createModule(Loc,
-                    getSILType(ModuleType::get(Mod), SILValueCategory::Object));
-    break;
-  }
   // Checked Conversion instructions.
   case ValueKind::UnconditionalCheckedCastInst: {
     SILValue Val = getLocalValue(ValID, ValResNum,
diff --git a/lib/Serialization/SerializeSIL.cpp b/lib/Serialization/SerializeSIL.cpp
index 96fba982ee9..05a5d693a26 100644
--- a/lib/Serialization/SerializeSIL.cpp
+++ b/lib/Serialization/SerializeSIL.cpp
@@ -663,16 +663,6 @@ void SILSerializer::writeSILInstruction(const SILInstruction &SI) {
                       (unsigned)MI->getType().getCategory());
     break;
   }
-  case ValueKind::ModuleInst: {
-    // Has IdentifierID for the module reference. Use SILOneTypeLayout.
-    const ModuleInst *MI = cast<ModuleInst>(&SI);
-    ModuleType *MT = MI->getType().castTo<ModuleType>();
-    SILOneTypeLayout::emitRecord(Out, ScratchRecord,
-                      SILAbbrCodes[SILOneTypeLayout::Code],
-                      (unsigned)SI.getKind(),
-                      S.addModuleRef(MT->getModule()), 0);
-    break;
-  }
   case ValueKind::ProjectExistentialInst: {
     const ProjectExistentialInst *PEI = cast<ProjectExistentialInst>(&SI);
     SILOneTypeOneOperandLayout::emitRecord(Out, ScratchRecord,
diff --git a/test/SIL/Parser/basic.sil b/test/SIL/Parser/basic.sil
index 559bebfb1fb..bb7725ebfe9 100644
--- a/test/SIL/Parser/basic.sil
+++ b/test/SIL/Parser/basic.sil
@@ -528,7 +528,6 @@ bb0(%0 : $Builtin.RawPointer, %1 : $Builtin.Int64):
   %3 = alloc_box $Builtin.Int64                   // CHECK: alloc_box
   %4 = store %0 to %2#1 : $*Builtin.RawPointer
   %5 = store %1 to %3#1 : $*Builtin.Int64
-  // %6 = module #Builtin
   %7 = load %2#1 : $*Builtin.RawPointer           // CHECK: load
   %8 = load %3#1 : $*Builtin.Int64                // CHECK: load
   // CHECK: index_raw_pointer {{%.*}} : $Builtin.RawPointer, {{%.*}} : $Builtin.Int64
@@ -672,7 +671,6 @@ bb0(%0 : $Builtin.Int1, %1 : $Builtin.Int1):
   %3 = alloc_box $Builtin.Int1
   store %0 to %2#1 : $*Builtin.Int1
   store %1 to %3#1 : $*Builtin.Int1
-  %6 = module #Builtin              // CHECK: module #Builtin
   // CHECK: builtin_function_ref #Builtin.cmp_eq_Int1 : $@thin (Builtin.Int1, Builtin.Int1) -> Builtin.Int1
   %7 = builtin_function_ref #Builtin.cmp_eq_Int1 : $@thin (Builtin.Int1, Builtin.Int1) -> Builtin.Int1
   %8 = load %2#1 : $*Builtin.Int1
@@ -988,7 +986,6 @@ bb0(%0 : $Int64, %1 : $Int64, %2 : $Foo):
   %8 = alloc_stack $Foo  // var self              // users: %15, %14, %9
   store %2 to %8#1 : $*Foo
   %10 = metatype $Int64.metatype
-  %11 = module #Builtin
   %12 = integer_literal $Builtin.Int64, 0         // user: %13
   %13 = struct $Int64 (%12 : $Builtin.Int64)      // user: %18
   destroy_addr %8#1 : $*Foo
diff --git a/test/Serialization/Inputs/def_basic.sil b/test/Serialization/Inputs/def_basic.sil
index 3180fa7be05..7c5bb8a3e07 100644
--- a/test/Serialization/Inputs/def_basic.sil
+++ b/test/Serialization/Inputs/def_basic.sil
@@ -456,7 +456,6 @@ bb0(%0 : $Builtin.RawPointer, %1 : $Builtin.Int64):
   %3 = alloc_box $Builtin.Int64
   %4 = store %0 to %2#1 : $*Builtin.RawPointer
   %5 = store %1 to %3#1 : $*Builtin.Int64
-  // %6 = module #Builtin
   %7 = load %2#1 : $*Builtin.RawPointer
   %8 = load %3#1 : $*Builtin.Int64
   // CHECK: index_raw_pointer {{%.*}} : $Builtin.RawPointer, {{%.*}} : $Builtin.Int64
@@ -666,7 +665,6 @@ bb0(%0 : $Builtin.Int1, %1 : $Builtin.Int1):
   %3 = alloc_box $Builtin.Int1
   store %0 to %2#1 : $*Builtin.Int1
   store %1 to %3#1 : $*Builtin.Int1
-  %6 = module #Builtin              // CHECK: module #Builtin
   // CHECK: builtin_function_ref #Builtin.cmp_eq_Int1 : $@thin (Builtin.Int1, Builtin.Int1) -> Builtin.Int1
   %7 = builtin_function_ref #Builtin.cmp_eq_Int1 : $@thin (Builtin.Int1, Builtin.Int1) -> Builtin.Int1
   %8 = load %2#1 : $*Builtin.Int1
@@ -953,7 +951,6 @@ bb0(%0 : $Int64, %1 : $Int64, %2 : $Foo):
   %8 = alloc_stack $Foo  // var self              // users: %15, %14, %9
   store %2 to %8#1 : $*Foo
   %10 = metatype $Int64.metatype
-  %11 = module #Builtin
   %12 = integer_literal $Builtin.Int64, 0         // user: %13
   %13 = struct $Int64 (%12 : $Builtin.Int64)      // user: %18
   destroy_addr %8#1 : $*Foo