diff --git a/GNUmakefile b/GNUmakefile
index b0840b6814..8dc03fb5c8 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -347,6 +347,7 @@ TEST_PACKAGES_FAST = \
 	go/ast \
 	go/format \
 	go/scanner \
+	go/token \
 	go/version \
 	hash \
 	hash/adler32 \
@@ -359,6 +360,7 @@ TEST_PACKAGES_FAST = \
 	math/cmplx \
 	net/http/internal/ascii \
 	net/mail \
+	net/url \
 	os \
 	path \
 	reflect \
@@ -480,7 +482,7 @@ TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_WINDOWS)
 TEST_IOFS := false
 endif
 
-TEST_SKIP_FLAG := -skip='TestExtraMethods|TestParseAndBytesRoundTrip/P256/Generic'
+TEST_SKIP_FLAG := -skip='TestExtraMethods|TestParseAndBytesRoundTrip/P256/Generic|TestParseQueryLimits|TestParseStrictIpv6'
 TEST_ADDITIONAL_FLAGS ?=
 
 # Test known-working standard library packages.
diff --git a/compiler/interface.go b/compiler/interface.go
index e63666834f..5f7e7e345b 100644
--- a/compiler/interface.go
+++ b/compiler/interface.go
@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"go/token"
 	"go/types"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -17,6 +18,12 @@ import (
 	"tinygo.org/x/go-llvm"
 )
 
+// numMethodHasMethodSet is a flag in bit 15 of the numMethod field (uint16) in
+// Named, Pointer, and Struct type descriptors. When set, an inline method set
+// is present in the type descriptor. Must match the constant in
+// src/internal/reflectlite/type.go.
+const numMethodHasMethodSet = 0x8000
+
 // Type kinds for basic types.
 // They must match the constants for the Kind type in src/reflect/type.go.
 var basicTypes = [...]uint8{
@@ -183,6 +190,16 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 		typeFieldTypes := []*types.Var{
 			types.NewVar(token.NoPos, nil, "kind", types.Typ[types.Int8]),
 		}
+		// Compute the method set value for types that support methods.
+		var methods []*types.Func
+		for i := 0; i < ms.Len(); i++ {
+			methods = append(methods, ms.At(i).Obj().(*types.Func))
+		}
+		methodSetType := types.NewStruct([]*types.Var{
+			types.NewVar(token.NoPos, nil, "length", types.Typ[types.Uintptr]),
+			types.NewVar(token.NoPos, nil, "methods", types.NewArray(types.Typ[types.UnsafePointer], int64(len(methods)))),
+		}, nil)
+		methodSetValue := c.getMethodSetValue(methods)
 		switch typ := typ.(type) {
 		case *types.Basic:
 			typeFieldTypes = append(typeFieldTypes,
@@ -199,6 +216,13 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "ptrTo", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "underlying", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "pkgpath", types.Typ[types.UnsafePointer]),
+			)
+			if len(methods) > 0 {
+				typeFieldTypes = append(typeFieldTypes,
+					types.NewVar(token.NoPos, nil, "methods", methodSetType),
+				)
+			}
+			typeFieldTypes = append(typeFieldTypes,
 				types.NewVar(token.NoPos, nil, "name", types.NewArray(types.Typ[types.Int8], int64(len(pkgname)+1+len(name)+1))),
 			)
 		case *types.Chan:
@@ -218,6 +242,11 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "numMethods", types.Typ[types.Uint16]),
 				types.NewVar(token.NoPos, nil, "elementType", types.Typ[types.UnsafePointer]),
 			)
+			if len(methods) > 0 {
+				typeFieldTypes = append(typeFieldTypes,
+					types.NewVar(token.NoPos, nil, "methods", methodSetType),
+				)
+			}
 		case *types.Array:
 			typeFieldTypes = append(typeFieldTypes,
 				types.NewVar(token.NoPos, nil, "numMethods", types.Typ[types.Uint16]),
@@ -242,11 +271,16 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "numFields", types.Typ[types.Uint16]),
 				types.NewVar(token.NoPos, nil, "fields", types.NewArray(c.getRuntimeType("structField"), int64(typ.NumFields()))),
 			)
+			if len(methods) > 0 {
+				typeFieldTypes = append(typeFieldTypes,
+					types.NewVar(token.NoPos, nil, "methods", methodSetType),
+				)
+			}
 		case *types.Interface:
 			typeFieldTypes = append(typeFieldTypes,
 				types.NewVar(token.NoPos, nil, "ptrTo", types.Typ[types.UnsafePointer]),
+				types.NewVar(token.NoPos, nil, "methods", methodSetType),
 			)
-			// TODO: methods
 		case *types.Signature:
 			typeFieldTypes = append(typeFieldTypes,
 				types.NewVar(token.NoPos, nil, "ptrTo", types.Typ[types.UnsafePointer]),
@@ -292,14 +326,24 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				pkgname = pkg.Name()
 			}
 			pkgPathPtr := c.pkgPathPtr(pkgpath)
+			namedNumMethods := uint64(numMethods)
+			if namedNumMethods&numMethodHasMethodSet != 0 {
+				panic("numMethods overflow: too many exported methods on named type " + name)
+			}
+			if len(methods) > 0 {
+				namedNumMethods |= numMethodHasMethodSet
+			}
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
-				c.getTypeCode(types.NewPointer(typ)),                        // ptrTo
-				c.getTypeCode(typ.Underlying()),                             // underlying
-				pkgPathPtr,                                                  // pkgpath pointer
-				c.ctx.ConstString(pkgname+"."+name+"\x00", false),           // name
+				llvm.ConstInt(c.ctx.Int16Type(), namedNumMethods, false), // numMethods
+				c.getTypeCode(types.NewPointer(typ)),                     // ptrTo
+				c.getTypeCode(typ.Underlying()),                          // underlying
+				pkgPathPtr,                                               // pkgpath pointer
 			}
-			metabyte |= 1 << 5 // "named" flag
+			if len(methods) > 0 {
+				typeFields = append(typeFields, methodSetValue) // methods
+			}
+			typeFields = append(typeFields, c.ctx.ConstString(pkgname+"."+name+"\x00", false)) // name
+			metabyte |= 1 << 5                                                                 // "named" flag
 		case *types.Chan:
 			var dir reflectChanDir
 			switch typ.Dir() {
@@ -323,10 +367,20 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				c.getTypeCode(typ.Elem()),                  // elementType
 			}
 		case *types.Pointer:
+			ptrNumMethods := uint64(numMethods)
+			if ptrNumMethods&numMethodHasMethodSet != 0 {
+				panic("numMethods overflow: too many exported methods on pointer type")
+			}
+			if len(methods) > 0 {
+				ptrNumMethods |= numMethodHasMethodSet
+			}
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
+				llvm.ConstInt(c.ctx.Int16Type(), ptrNumMethods, false), // numMethods
 				c.getTypeCode(typ.Elem()),
 			}
+			if len(methods) > 0 {
+				typeFields = append(typeFields, methodSetValue)
+			}
 		case *types.Array:
 			typeFields = []llvm.Value{
 				llvm.ConstInt(c.ctx.Int16Type(), 0, false),             // numMethods
@@ -353,9 +407,16 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 
 			llvmStructType := c.getLLVMType(typ)
 			size := c.targetData.TypeStoreSize(llvmStructType)
+			structNumMethods := uint64(numMethods)
+			if structNumMethods&numMethodHasMethodSet != 0 {
+				panic("numMethods overflow: too many exported methods on struct type")
+			}
+			if len(methods) > 0 {
+				structNumMethods |= numMethodHasMethodSet
+			}
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
-				c.getTypeCode(types.NewPointer(typ)),                        // ptrTo
+				llvm.ConstInt(c.ctx.Int16Type(), structNumMethods, false), // numMethods
+				c.getTypeCode(types.NewPointer(typ)),                      // ptrTo
 				pkgPathPtr,
 				llvm.ConstInt(c.ctx.Int32Type(), uint64(size), false),            // size
 				llvm.ConstInt(c.ctx.Int16Type(), uint64(typ.NumFields()), false), // numFields
@@ -407,9 +468,14 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				}))
 			}
 			typeFields = append(typeFields, llvm.ConstArray(structFieldType, fields))
+			if len(methods) > 0 {
+				typeFields = append(typeFields, methodSetValue)
+			}
 		case *types.Interface:
-			typeFields = []llvm.Value{c.getTypeCode(types.NewPointer(typ))}
-			// TODO: methods
+			typeFields = []llvm.Value{
+				c.getTypeCode(types.NewPointer(typ)),
+				methodSetValue,
+			}
 		case *types.Signature:
 			typeFields = []llvm.Value{c.getTypeCode(types.NewPointer(typ))}
 			// TODO: params, return values, etc
@@ -696,17 +762,11 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 			// This type assertion always succeeds, so we can just set commaOk to true.
 			commaOk = llvm.ConstInt(b.ctx.Int1Type(), 1, true)
 		} else {
-			// Type assert on interface type with methods.
-			// This is a call to an interface type assert function.
-			// The interface lowering pass will define this function by filling it
-			// with a type switch over all concrete types that implement this
-			// interface, and returning whether it's one of the matched types.
-			// This is very different from how interface asserts are implemented in
-			// the main Go compiler, where the runtime checks whether the type
-			// implements each method of the interface. See:
-			// https://research.swtch.com/interfaces
-			fn := b.getInterfaceImplementsFunc(expr.AssertedType)
-			commaOk = b.CreateCall(fn.GlobalValueType(), fn, []llvm.Value{actualTypeNum}, "")
+			// Type assert on an interface type with methods.
+			// Create a call to a declared-but-not-defined function that will
+			// be lowered by the interface lowering pass into a type-ID
+			// comparison chain.
+			commaOk = b.createInterfaceTypeAssert(intf, actualTypeNum)
 		}
 	} else {
 		name, _ := getTypeCodeName(expr.AssertedType)
@@ -783,20 +843,58 @@ func (c *compilerContext) getMethodsString(itf *types.Interface) string {
 	return strings.Join(methods, "; ")
 }
 
-// getInterfaceImplementsFunc returns a declared function that works as a type
-// switch. The interface lowering pass will define this function.
-func (c *compilerContext) getInterfaceImplementsFunc(assertedType types.Type) llvm.Value {
-	s, _ := getTypeCodeName(assertedType.Underlying())
-	fnName := s + ".$typeassert"
-	llvmFn := c.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		llvmFnType := llvm.FunctionType(c.ctx.Int1Type(), []llvm.Type{c.dataPtrType}, false)
-		llvmFn = llvm.AddFunction(c.mod, fnName, llvmFnType)
-		c.addStandardDeclaredAttributes(llvmFn)
-		methods := c.getMethodsString(assertedType.Underlying().(*types.Interface))
-		llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("tinygo-methods", methods))
+// getMethodSetValue creates the method set struct value for a list of methods.
+// The struct contains a length and a sorted array of method signature pointers.
+func (c *compilerContext) getMethodSetValue(methods []*types.Func) llvm.Value {
+	// Create a sorted list of method signature global names.
+	type methodRef struct {
+		name  string
+		value llvm.Value
 	}
-	return llvmFn
+	var refs []methodRef
+	for _, method := range methods {
+		name := method.Name()
+		if !token.IsExported(name) {
+			name = method.Pkg().Path() + "." + name
+		}
+		s, _ := getTypeCodeName(method.Type())
+		globalName := "reflect/types.signature:" + name + ":" + s
+		value := c.mod.NamedGlobal(globalName)
+		if value.IsNil() {
+			value = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), globalName)
+			value.SetInitializer(llvm.ConstNull(c.ctx.Int8Type()))
+			value.SetGlobalConstant(true)
+			value.SetLinkage(llvm.LinkOnceODRLinkage)
+			value.SetAlignment(1)
+			if c.Debug {
+				file := c.getDIFile("<Go type>")
+				diglobal := c.dibuilder.CreateGlobalVariableExpression(file, llvm.DIGlobalVariableExpression{
+					Name:        globalName,
+					File:        file,
+					Line:        1,
+					Type:        c.getDIType(types.Typ[types.Uint8]),
+					LocalToUnit: false,
+					Expr:        c.dibuilder.CreateExpression(nil),
+					AlignInBits: 8,
+				})
+				value.AddMetadata(0, diglobal)
+			}
+		}
+		refs = append(refs, methodRef{globalName, value})
+	}
+	sort.Slice(refs, func(i, j int) bool {
+		return refs[i].name < refs[j].name
+	})
+
+	var values []llvm.Value
+	for _, ref := range refs {
+		values = append(values, ref.value)
+	}
+
+	return c.ctx.ConstStruct([]llvm.Value{
+		llvm.ConstInt(c.uintptrType, uint64(len(values)), false),
+		llvm.ConstArray(c.dataPtrType, values),
+	}, false)
 }
 
 // getInvokeFunction returns the thunk to call the given interface method. The
@@ -823,6 +921,24 @@ func (c *compilerContext) getInvokeFunction(instr *ssa.CallCommon) llvm.Value {
 	return llvmFn
 }
 
+// createInterfaceTypeAssert creates a call to a declared-but-not-defined
+// $typeassert function for the given interface. This function will be defined
+// by the interface lowering pass as a type-ID comparison chain, avoiding the
+// need for runtime.typeImplementsMethodSet at compile time.
+func (b *builder) createInterfaceTypeAssert(intf *types.Interface, actualType llvm.Value) llvm.Value {
+	s, _ := getTypeCodeName(intf)
+	fnName := s + ".$typeassert"
+	llvmFn := b.mod.NamedFunction(fnName)
+	if llvmFn.IsNil() {
+		llvmFnType := llvm.FunctionType(b.ctx.Int1Type(), []llvm.Type{b.dataPtrType}, false)
+		llvmFn = llvm.AddFunction(b.mod, fnName, llvmFnType)
+		b.addStandardDeclaredAttributes(llvmFn)
+		methods := b.getMethodsString(intf)
+		llvmFn.AddFunctionAttr(b.ctx.CreateStringAttribute("tinygo-methods", methods))
+	}
+	return b.CreateCall(llvmFn.GlobalValueType(), llvmFn, []llvm.Value{actualType}, "")
+}
+
 // getInterfaceInvokeWrapper returns a wrapper for the given method so it can be
 // invoked from an interface. The wrapper takes in a pointer to the underlying
 // value, dereferences or unpacks it if necessary, and calls the real method.
diff --git a/compiler/testdata/interface.ll b/compiler/testdata/interface.ll
index fcde0158d4..4bec11c419 100644
--- a/compiler/testdata/interface.ll
+++ b/compiler/testdata/interface.ll
@@ -9,12 +9,14 @@ target triple = "wasm32-unknown-wasi"
 @"reflect/types.type:basic:int" = linkonce_odr constant { i8, ptr } { i8 -62, ptr @"reflect/types.type:pointer:basic:int" }, align 4
 @"reflect/types.type:pointer:basic:int" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:basic:int" }, align 4
 @"reflect/types.type:pointer:named:error" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:named:error" }, align 4
-@"reflect/types.type:named:error" = linkonce_odr constant { i8, i16, ptr, ptr, ptr, [7 x i8] } { i8 116, i16 1, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}", ptr @"reflect/types.type.pkgpath.empty", [7 x i8] c".error\00" }, align 4
+@"reflect/types.signature:Error:func:{}{basic:string}" = linkonce_odr constant i8 0, align 1
+@"reflect/types.type:named:error" = linkonce_odr constant { i8, i16, ptr, ptr, ptr, { i32, [1 x ptr] }, [7 x i8] } { i8 116, i16 -32767, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}", ptr @"reflect/types.type.pkgpath.empty", { i32, [1 x ptr] } { i32 1, [1 x ptr] [ptr @"reflect/types.signature:Error:func:{}{basic:string}"] }, [7 x i8] c".error\00" }, align 4
 @"reflect/types.type.pkgpath.empty" = linkonce_odr unnamed_addr constant [1 x i8] zeroinitializer, align 1
-@"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant { i8, ptr } { i8 84, ptr @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }, align 4
+@"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant { i8, ptr, { i32, [1 x ptr] } } { i8 84, ptr @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}", { i32, [1 x ptr] } { i32 1, [1 x ptr] [ptr @"reflect/types.signature:Error:func:{}{basic:string}"] } }, align 4
 @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4
 @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:interface:{String:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:interface:{String:func:{}{basic:string}}" = linkonce_odr constant { i8, ptr } { i8 84, ptr @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" }, align 4
+@"reflect/types.signature:String:func:{}{basic:string}" = linkonce_odr constant i8 0, align 1
+@"reflect/types.type:interface:{String:func:{}{basic:string}}" = linkonce_odr constant { i8, ptr, { i32, [1 x ptr] } } { i8 84, ptr @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}", { i32, [1 x ptr] } { i32 1, [1 x ptr] [ptr @"reflect/types.signature:String:func:{}{basic:string}"] } }, align 4
 @"reflect/types.typeid:basic:int" = external constant i8
 
 ; Function Attrs: allockind("alloc,zeroed") allocsize(0)
diff --git a/interp/interpreter.go b/interp/interpreter.go
index 137938d9f3..e8f5545d5d 100644
--- a/interp/interpreter.go
+++ b/interp/interpreter.go
@@ -413,64 +413,6 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				// Special function that will trigger an error.
 				// This is used to test error reporting.
 				return nil, mem, r.errorAt(inst, errors.New("test error"))
-			case strings.HasSuffix(callFn.name, ".$typeassert"):
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"interface assert:", operands[1:])
-				}
-
-				// Load various values for the interface implements check below.
-				typecodePtr, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				// typecodePtr always point to the numMethod field in the type
-				// description struct. The methodSet, when present, comes right
-				// before the numMethod field (the compiler doesn't generate
-				// method sets for concrete types without methods).
-				// Considering that the compiler doesn't emit interface type
-				// asserts for interfaces with no methods (as the always succeed)
-				// then if the offset is zero, this assert must always fail.
-				if typecodePtr.offset() == 0 {
-					locals[inst.localIndex] = literalValue{uint8(0)}
-					break
-				}
-				typecodePtrOffset, err := typecodePtr.addOffset(-int64(r.pointerSize))
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				methodSetPtr, err := mem.load(typecodePtrOffset, r.pointerSize).asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				methodSet := mem.get(methodSetPtr.index()).llvmGlobal.Initializer()
-				numMethods := int(r.builder.CreateExtractValue(methodSet, 0, "").ZExtValue())
-				llvmFn := inst.llvmInst.CalledValue()
-				methodSetAttr := llvmFn.GetStringAttributeAtIndex(-1, "tinygo-methods")
-				methodSetString := methodSetAttr.GetStringValue()
-
-				// Make a set of all the methods on the concrete type, for
-				// easier checking in the next step.
-				concreteTypeMethods := map[string]struct{}{}
-				for i := 0; i < numMethods; i++ {
-					methodInfo := r.builder.CreateExtractValue(methodSet, 1, "")
-					name := r.builder.CreateExtractValue(methodInfo, i, "").Name()
-					concreteTypeMethods[name] = struct{}{}
-				}
-
-				// Check whether all interface methods are also in the list
-				// of defined methods calculated above. This is the interface
-				// assert itself.
-				assertOk := uint8(1) // i1 true
-				for _, name := range strings.Split(methodSetString, "; ") {
-					if _, ok := concreteTypeMethods[name]; !ok {
-						// There is a method on the interface that is not
-						// implemented by the type. The assertion will fail.
-						assertOk = 0 // i1 false
-						break
-					}
-				}
-				// If assertOk is still 1, the assertion succeeded.
-				locals[inst.localIndex] = literalValue{assertOk}
 			case strings.HasSuffix(callFn.name, "$invoke"):
 				// This thunk is the interface method dispatcher: it is called
 				// with all regular parameters and a type code. It will then
diff --git a/src/internal/reflectlite/type.go b/src/internal/reflectlite/type.go
index 6795a51b2c..e282f16f3b 100644
--- a/src/internal/reflectlite/type.go
+++ b/src/internal/reflectlite/type.go
@@ -157,6 +157,10 @@ const (
 	flagIsBinary   = 128 // flag that is set if this type uses the hashmap binary algorithm
 )
 
+// Flag in the numMethod field (uint16) of Pointer and Struct type descriptors,
+// indicating that an inline method set is present in the type descriptor.
+const numMethodHasMethodSet = 0x8000
+
 // The base type struct. All type structs start with this.
 type RawType struct {
 	meta uint8 // metadata byte, contains kind and flags (see constants above)
@@ -171,16 +175,22 @@ type elemType struct {
 	elem      *RawType
 }
 
+// ptrType is the type descriptor for pointer types.
+// The numMethod field stores the number of exported methods in the lower bits,
+// with bit 15 (numMethodHasMethodSet) indicating whether the methods field is
+// present. When the flag is clear, the methods field does not exist in the
+// actual type descriptor and must not be accessed.
 type ptrType struct {
 	RawType
 	numMethod uint16
 	elem      *RawType
+	methods   methodSet // only present when numMethod & numMethodHasMethodSet != 0
 }
 
 type interfaceType struct {
 	RawType
-	ptrTo *RawType
-	// TODO: methods
+	ptrTo   *RawType
+	methods methodSet
 }
 
 type arrayType struct {
@@ -200,13 +210,19 @@ type mapType struct {
 	key       *RawType
 }
 
+// namedType is the type descriptor for named types. The numMethod field uses
+// bit 15 (numMethodHasMethodSet) to indicate whether an inline method set is
+// present after pkg. When the flag is set, a methodSet follows at
+// unsafe.Sizeof(namedType{}), and the name string follows after the method
+// set's entries. When clear, the name string starts directly at that offset.
 type namedType struct {
 	RawType
 	numMethod uint16
 	ptrTo     *RawType
 	elem      *RawType
 	pkg       *byte
-	name      [1]byte
+	// if numMethod & numMethodHasMethodSet != 0: methodSet follows here
+	// name (null-terminated "pkg.Name\0") follows after the method set (or directly here)
 }
 
 // Type for struct types. The numField value is intentionally put before ptrTo
@@ -216,6 +232,10 @@ type namedType struct {
 // The fields array isn't necessarily 1 structField long, instead it is as long
 // as numFields. The array is given a length of 1 to satisfy the Go type
 // checker.
+// The numMethod field stores the number of exported methods in the lower bits,
+// with bit 15 (numMethodHasMethodSet) indicating whether an inline method set
+// follows the fields array. When the flag is clear, no method set is present
+// and the type descriptor ends after the last structField entry.
 type structType struct {
 	RawType
 	numMethod uint16
@@ -224,6 +244,7 @@ type structType struct {
 	size      uint32
 	numField  uint16
 	fields    [1]structField // the remaining fields are all of type structField
+	// methods methodSet follows after fields, only when numMethod & numMethodHasMethodSet != 0
 }
 
 type structField struct {
@@ -231,6 +252,12 @@ type structField struct {
 	data      unsafe.Pointer // various bits of information, packed in a byte array
 }
 
+// Method set, as emitted by the compiler.
+type methodSet struct {
+	length  uintptr
+	methods [0]unsafe.Pointer // variable number of method signature pointers
+}
+
 // Equivalent to (go/types.Type).Underlying(): if this is a named type return
 // the underlying type, else just return the type itself.
 func (t *RawType) underlying() *RawType {
@@ -733,21 +760,38 @@ func (t *RawType) FieldAlign() int {
 // AssignableTo returns whether a value of type t can be assigned to a variable
 // of type u.
 func (t *RawType) AssignableTo(u Type) bool {
-	if t == u.(*RawType) {
+	u_raw := u.(*RawType)
+	if t == u_raw {
 		return true
 	}
 
-	if t.underlying() == u.(*RawType).underlying() && (!t.isNamed() || !u.(*RawType).isNamed()) {
-		return true
+	if u.Kind() == Interface {
+		// T is an interface type and x implements T.
+		u_itf := (*interfaceType)(unsafe.Pointer(u_raw.underlying()))
+		return typeImplementsMethodSet(unsafe.Pointer(t), unsafe.Pointer(&u_itf.methods))
 	}
 
-	if u.Kind() == Interface && u.NumMethod() == 0 {
+	t_named := t.isNamed()
+	u_named := u_raw.isNamed()
+	if t_named && u_named {
+		return false
+	}
+	if t.underlying() == u_raw.underlying() {
 		return true
 	}
 
-	if u.Kind() == Interface {
-		panic("reflect: unimplemented: AssignableTo with interface")
+	if t.Kind() == Chan && u_raw.Kind() == Chan {
+		t_chan := (*elemType)(unsafe.Pointer(t.underlying()))
+		u_chan := (*elemType)(unsafe.Pointer(u_raw.underlying()))
+		if t_chan.elem != u_chan.elem {
+			return false
+		}
+		if t_chan.ChanDir() != BothDir {
+			return false
+		}
+		return true
 	}
+
 	return false
 }
 
@@ -755,7 +799,85 @@ func (t *RawType) Implements(u Type) bool {
 	if u.Kind() != Interface {
 		panic("reflect: non-interface type passed to Type.Implements")
 	}
-	return t.AssignableTo(u)
+	u_itf := (*interfaceType)(unsafe.Pointer(u.(*RawType).underlying()))
+	return typeImplementsMethodSet(unsafe.Pointer(t), unsafe.Pointer(&u_itf.methods))
+}
+
+// typeImplementsMethodSet checks whether the concrete type (identified by its
+// typecode pointer) implements the given method set. Both the concrete type's
+// method set and the asserted method set are sorted arrays of method signature
+// pointers, so comparison is O(n+m).
+//
+//go:linkname typeImplementsMethodSet runtime.typeImplementsMethodSet
+func typeImplementsMethodSet(concreteType, assertedMethodSet unsafe.Pointer) bool {
+	if concreteType == nil {
+		return false
+	}
+
+	const ptrSize = unsafe.Sizeof((*byte)(nil))
+	itfNumMethod := *(*uintptr)(assertedMethodSet)
+	if itfNumMethod == 0 {
+		return true
+	}
+
+	// Pull the method set out of the concrete type.
+	var methods *methodSet
+	metaByte := *(*uint8)(concreteType)
+	if metaByte&flagNamed != 0 {
+		ct := (*namedType)(concreteType)
+		if ct.numMethod&numMethodHasMethodSet == 0 {
+			return false
+		}
+		methods = (*methodSet)(unsafe.Add(unsafe.Pointer(ct), unsafe.Sizeof(*ct)))
+	} else if metaByte&kindMask == uint8(Interface) {
+		ct := (*interfaceType)(concreteType)
+		methods = &ct.methods
+	} else if metaByte&kindMask == uint8(Pointer) {
+		ct := (*ptrType)(concreteType)
+		if ct.numMethod&numMethodHasMethodSet == 0 {
+			return false
+		}
+		methods = &ct.methods
+	} else if metaByte&kindMask == uint8(Struct) {
+		ct := (*structType)(concreteType)
+		if ct.numMethod&numMethodHasMethodSet == 0 {
+			return false
+		}
+		// For struct types, the method set follows after the variable-length
+		// fields array. We need to compute its offset dynamically.
+		fieldSize := unsafe.Sizeof(structField{})
+		methodsPtr := unsafe.Add(unsafe.Pointer(&ct.fields[0]), uintptr(ct.numField)*fieldSize)
+		methods = (*methodSet)(methodsPtr)
+	} else {
+		return false
+	}
+
+	concreteTypePtr := unsafe.Pointer(&methods.methods)
+	concreteTypeEnd := unsafe.Add(concreteTypePtr, uintptr(methods.length)*ptrSize)
+
+	// Iterate over each method in the interface method set, and check whether
+	// the method exists in the method set of the concrete type.
+	// Both method sets are sorted, so we can use a linear scan.
+	assertedTypePtr := unsafe.Add(assertedMethodSet, ptrSize)
+	assertedTypeEnd := unsafe.Add(assertedTypePtr, itfNumMethod*ptrSize)
+	for assertedTypePtr != assertedTypeEnd {
+		assertedMethod := *(*unsafe.Pointer)(assertedTypePtr)
+
+		for {
+			if concreteTypePtr == concreteTypeEnd {
+				return false
+			}
+			concreteMethod := *(*unsafe.Pointer)(concreteTypePtr)
+			concreteTypePtr = unsafe.Add(concreteTypePtr, ptrSize)
+			if concreteMethod == assertedMethod {
+				break
+			}
+		}
+
+		assertedTypePtr = unsafe.Add(assertedTypePtr, ptrSize)
+	}
+
+	return true
 }
 
 // Comparable returns whether values of this type can be compared to each other.
@@ -782,14 +904,14 @@ func (t *RawType) ChanDir() ChanDir {
 func (t *RawType) NumMethod() int {
 
 	if t.isNamed() {
-		return int((*namedType)(unsafe.Pointer(t)).numMethod)
+		return int((*namedType)(unsafe.Pointer(t)).numMethod & ^uint16(numMethodHasMethodSet))
 	}
 
 	switch t.Kind() {
 	case Pointer:
-		return int((*ptrType)(unsafe.Pointer(t)).numMethod)
+		return int((*ptrType)(unsafe.Pointer(t)).numMethod & ^uint16(numMethodHasMethodSet))
 	case Struct:
-		return int((*structType)(unsafe.Pointer(t)).numMethod)
+		return int((*structType)(unsafe.Pointer(t)).numMethod & ^uint16(numMethodHasMethodSet))
 	case Interface:
 		//FIXME: Use len(methods)
 		return (*interfaceType)(unsafe.Pointer(t)).ptrTo.NumMethod()
@@ -816,7 +938,14 @@ func readStringZ(data unsafe.Pointer) string {
 
 func (t *RawType) name() string {
 	ntype := (*namedType)(unsafe.Pointer(t))
-	return readStringZ(unsafe.Pointer(&ntype.name[0]))
+	// The name follows after the fixed fields (and optionally the method set).
+	ptr := unsafe.Add(unsafe.Pointer(ntype), unsafe.Sizeof(*ntype))
+	if ntype.numMethod&numMethodHasMethodSet != 0 {
+		ms := (*methodSet)(ptr)
+		// Skip past the length field and the method pointer entries.
+		ptr = unsafe.Add(ptr, unsafe.Sizeof(uintptr(0))+uintptr(ms.length)*unsafe.Sizeof(unsafe.Pointer(nil)))
+	}
+	return readStringZ(ptr)
 }
 
 func (t *RawType) Name() string {
diff --git a/src/runtime/interface.go b/src/runtime/interface.go
index e1d263a7e3..e487c46c2f 100644
--- a/src/runtime/interface.go
+++ b/src/runtime/interface.go
@@ -90,6 +90,9 @@ func interfaceTypeAssert(ok bool) {
 	}
 }
 
+// Implemented in the internal/reflectlite package.
+func typeImplementsMethodSet(actualTypeNum, assertedMethodSet unsafe.Pointer) bool
+
 // The following declarations are only used during IR construction. They are
 // lowered to inline IR in the interface lowering pass.
 // See compiler/interface-lowering.go for details.
diff --git a/testdata/reflect.go b/testdata/reflect.go
index 6971866dbd..873d60f787 100644
--- a/testdata/reflect.go
+++ b/testdata/reflect.go
@@ -344,12 +344,8 @@ func main() {
 		println("PtrTo failed for type myslice")
 	}
 
-	if reflect.TypeOf(errorValue).Implements(errorType) != true {
-		println("errorValue.Implements(errorType) was false, expected true")
-	}
-	if reflect.TypeOf(errorValue).Implements(stringerType) != false {
-		println("errorValue.Implements(errorType) was true, expected false")
-	}
+	println("\ninterface implements")
+	testImplements()
 
 	println("\nalignment / offset:")
 	v2 := struct {
@@ -573,6 +569,230 @@ func testInterfaceMethod() {
 	}
 }
 
+// Types for interface Implements/AssignableTo tests.
+
+type Reader interface {
+	Read(p []byte) (n int, err error)
+}
+
+type Writer interface {
+	Write(p []byte) (n int, err error)
+}
+
+type ReadWriter interface {
+	Read(p []byte) (n int, err error)
+	Write(p []byte) (n int, err error)
+}
+
+type Closer interface {
+	Close() error
+}
+
+type ReadCloser interface {
+	Read(p []byte) (n int, err error)
+	Close() error
+}
+
+type myReader struct{}
+
+func (myReader) Read(p []byte) (int, error) { return 0, nil }
+
+type myWriter struct{}
+
+func (*myWriter) Write(p []byte) (int, error) { return 0, nil }
+
+type myReadWriter struct{}
+
+func (myReadWriter) Read(p []byte) (int, error)   { return 0, nil }
+func (*myReadWriter) Write(p []byte) (int, error)  { return 0, nil }
+
+type myStringer struct{}
+
+func (myStringer) String() string { return "mystringer" }
+
+type myErrorStringer struct{}
+
+func (myErrorStringer) Error() string  { return "err" }
+func (myErrorStringer) String() string { return "str" }
+
+// Interface with unexported method (from upstream set_test.go).
+type exprLike interface {
+	Pos() int
+	End() int
+	exprNode()
+}
+
+type notAnExpr struct{}
+
+func (notAnExpr) Pos() int  { return 0 }
+func (notAnExpr) End() int  { return 0 }
+func (notAnExpr) exprNode() {}
+
+// Named types for assignability tests (from upstream set_test.go).
+type IntPtr *int
+type IntPtr1 *int
+type Ch <-chan interface{}
+
+func testImplements() {
+	readerType := reflect.TypeOf((*Reader)(nil)).Elem()
+	writerType := reflect.TypeOf((*Writer)(nil)).Elem()
+	readWriterType := reflect.TypeOf((*ReadWriter)(nil)).Elem()
+	closerType := reflect.TypeOf((*Closer)(nil)).Elem()
+	readCloserType := reflect.TypeOf((*ReadCloser)(nil)).Elem()
+	emptyItf := reflect.TypeOf((*interface{})(nil)).Elem()
+
+	// --- Concrete type implements interface ---
+	println("concrete implements:")
+
+	// myReader has value receiver Read → implements Reader
+	println("myReader → Reader:", reflect.TypeOf(myReader{}).Implements(readerType))           // true
+	println("*myReader → Reader:", reflect.TypeOf(new(myReader)).Elem().Implements(readerType)) // true (value method in pointer set)
+
+	// myWriter has pointer receiver Write → only *myWriter implements Writer
+	println("myWriter → Writer:", reflect.TypeOf(myWriter{}).Implements(writerType))    // false (pointer receiver)
+	println("*myWriter → Writer:", reflect.TypeOf(&myWriter{}).Implements(writerType))  // true
+
+	// myReadWriter: Read on value, Write on pointer
+	println("myReadWriter → Reader:", reflect.TypeOf(myReadWriter{}).Implements(readerType))      // true
+	println("myReadWriter → Writer:", reflect.TypeOf(myReadWriter{}).Implements(writerType))      // false (Write is ptr recv)
+	println("myReadWriter → ReadWriter:", reflect.TypeOf(myReadWriter{}).Implements(readWriterType)) // false
+	println("*myReadWriter → Reader:", reflect.TypeOf(&myReadWriter{}).Implements(readerType))       // true
+	println("*myReadWriter → Writer:", reflect.TypeOf(&myReadWriter{}).Implements(writerType))       // true
+	println("*myReadWriter → ReadWriter:", reflect.TypeOf(&myReadWriter{}).Implements(readWriterType)) // true
+
+	// Nothing implements Closer (none of our types have Close)
+	println("myReader → Closer:", reflect.TypeOf(myReader{}).Implements(closerType))             // false
+	println("*myReadWriter → Closer:", reflect.TypeOf(&myReadWriter{}).Implements(closerType))   // false
+
+	// errorValue (*errors.errorString) implements error but not Stringer
+	println("errorValue → error:", reflect.TypeOf(errorValue).Implements(errorType))       // true
+	println("errorValue → Stringer:", reflect.TypeOf(errorValue).Implements(stringerType)) // false
+
+	// myErrorStringer implements both error and Stringer
+	println("myErrorStringer → error:", reflect.TypeOf(myErrorStringer{}).Implements(errorType))       // true
+	println("myErrorStringer → Stringer:", reflect.TypeOf(myErrorStringer{}).Implements(stringerType)) // true
+
+	// Everything implements empty interface
+	println("myReader → interface{}:", reflect.TypeOf(myReader{}).Implements(emptyItf))   // true
+	println("int → interface{}:", reflect.TypeOf(0).Implements(emptyItf))                 // true
+
+	// --- Interface implements interface (superset check, issue #3580) ---
+	println("interface implements interface:")
+
+	// ReadWriter is a superset of Reader and Writer
+	println("ReadWriter → Reader:", readWriterType.Implements(readerType))         // true
+	println("ReadWriter → Writer:", readWriterType.Implements(writerType))         // true
+	println("Reader → ReadWriter:", readerType.Implements(readWriterType))         // false
+	println("Writer → ReadWriter:", writerType.Implements(readWriterType))         // false
+
+	// ReadCloser has Read+Close, Reader has Read
+	println("ReadCloser → Reader:", readCloserType.Implements(readerType))         // true
+	println("ReadCloser → Closer:", readCloserType.Implements(closerType))         // true
+	println("ReadCloser → Writer:", readCloserType.Implements(writerType))         // false
+	println("Reader → ReadCloser:", readerType.Implements(readCloserType))         // false
+
+	// Self-implements
+	println("Reader → Reader:", readerType.Implements(readerType))                 // true
+	println("ReadWriter → ReadWriter:", readWriterType.Implements(readWriterType)) // true
+
+	// error and Stringer are unrelated
+	println("error → Stringer:", errorType.Implements(stringerType)) // false
+	println("Stringer → error:", stringerType.Implements(errorType)) // false
+
+	// Everything implements empty interface
+	println("Reader → interface{}:", readerType.Implements(emptyItf))       // true
+	println("ReadWriter → interface{}:", readWriterType.Implements(emptyItf)) // true
+
+	// --- AssignableTo ---
+	println("assignable to:")
+
+	// Identical types
+	println("int → int:", reflect.TypeOf(0).AssignableTo(reflect.TypeOf(0)))          // true
+	println("string → string:", reflect.TypeOf("").AssignableTo(reflect.TypeOf("")))   // true
+
+	// Different types
+	println("int → string:", reflect.TypeOf(0).AssignableTo(reflect.TypeOf("")))      // false
+	println("int → int64:", reflect.TypeOf(0).AssignableTo(reflect.TypeOf(int64(0)))) // false
+
+	// Concrete assignable to interface (implements check)
+	println("myReader → Reader:", reflect.TypeOf(myReader{}).AssignableTo(readerType))         // true
+	println("*myWriter → Writer:", reflect.TypeOf(&myWriter{}).AssignableTo(writerType))       // true
+	println("myWriter → Writer:", reflect.TypeOf(myWriter{}).AssignableTo(writerType))         // false
+	println("*myReadWriter → ReadWriter:", reflect.TypeOf(&myReadWriter{}).AssignableTo(readWriterType)) // true
+
+	// Interface assignable to interface
+	println("ReadWriter → Reader:", readWriterType.AssignableTo(readerType))         // true
+	println("Reader → ReadWriter:", readerType.AssignableTo(readWriterType))         // false
+
+	// Everything assignable to empty interface
+	println("int → interface{}:", reflect.TypeOf(0).AssignableTo(emptyItf))             // true
+	println("Reader → interface{}:", readerType.AssignableTo(emptyItf))                 // true
+
+	// --- Upstream set_test.go: unexported method interfaces ---
+	println("unexported method interface:")
+	exprType := reflect.TypeOf((*exprLike)(nil)).Elem()
+	println("*notAnExpr → exprLike:", reflect.TypeOf(new(notAnExpr)).Implements(exprType))       // true
+	println("notAnExpr → exprLike:", reflect.TypeOf(notAnExpr{}).Implements(exprType))            // true
+	println("*notAnExpr → exprLike (AssignableTo):", reflect.TypeOf(new(notAnExpr)).AssignableTo(exprType)) // true
+
+	// --- Upstream set_test.go: channel direction assignability ---
+	println("channel direction:")
+	println("chan int → <-chan int:", reflect.TypeOf(make(chan int)).AssignableTo(reflect.TypeOf(make(<-chan int))))    // true
+	println("<-chan int → chan int:", reflect.TypeOf(make(<-chan int)).AssignableTo(reflect.TypeOf(make(chan int))))    // false
+
+	// --- Upstream set_test.go: named type assignability ---
+	println("named types:")
+	println("*int → IntPtr:", reflect.TypeOf(new(int)).AssignableTo(reflect.TypeOf(IntPtr(nil))))     // true
+	println("IntPtr → *int:", reflect.TypeOf(IntPtr(nil)).AssignableTo(reflect.TypeOf(new(int))))     // true
+	println("IntPtr → IntPtr1:", reflect.TypeOf(IntPtr(nil)).AssignableTo(reflect.TypeOf(IntPtr1(nil)))) // false
+	println("Ch → <-chan interface{}:", reflect.TypeOf(Ch(nil)).AssignableTo(reflect.TypeOf(make(<-chan interface{})))) // true
+
+	// --- reflect.Value.Set with interface (issue #4277) ---
+	println("value set interface:")
+	type Node interface{ node() }
+	type FooNode struct{ V int }
+	type BarNode struct{ V int }
+	// Make FooNode and BarNode implement Node with pointer receivers
+	// (can't add methods to local types in function, use a different approach)
+	testValueSetInterface()
+}
+
+type IfaceNode interface {
+	ifaceNode()
+}
+type FooNode struct{ V int }
+type BarNode struct{ V int }
+
+func (*FooNode) ifaceNode() {}
+func (*BarNode) ifaceNode() {}
+
+type NodeContainer struct {
+	Nodes []IfaceNode
+}
+
+func testValueSetInterface() {
+	c := &NodeContainer{
+		Nodes: []IfaceNode{&FooNode{V: 1}, &FooNode{V: 2}},
+	}
+
+	// Use reflect to replace elements
+	v := reflect.ValueOf(c).Elem().FieldByName("Nodes")
+	v.Index(0).Set(reflect.ValueOf(&BarNode{V: 10}))
+
+	switch n := c.Nodes[0].(type) {
+	case *BarNode:
+		println("Set[0] to BarNode:", n.V) // 10
+	default:
+		println("FAIL: expected *BarNode")
+	}
+	switch n := c.Nodes[1].(type) {
+	case *FooNode:
+		println("Set[1] still FooNode:", n.V) // 2
+	default:
+		println("FAIL: expected *FooNode")
+	}
+}
+
 var xorshift32State uint32 = 1
 
 func xorshift32(x uint32) uint32 {
diff --git a/testdata/reflect.txt b/testdata/reflect.txt
index 90ac42ac98..3024568c3d 100644
--- a/testdata/reflect.txt
+++ b/testdata/reflect.txt
@@ -439,6 +439,70 @@ offset for int64 matches: true
 offset for complex128 matches: true
 type assertion succeeded for unreferenced type
 
+interface implements
+concrete implements:
+myReader → Reader: true
+*myReader → Reader: true
+myWriter → Writer: false
+*myWriter → Writer: true
+myReadWriter → Reader: true
+myReadWriter → Writer: false
+myReadWriter → ReadWriter: false
+*myReadWriter → Reader: true
+*myReadWriter → Writer: true
+*myReadWriter → ReadWriter: true
+myReader → Closer: false
+*myReadWriter → Closer: false
+errorValue → error: true
+errorValue → Stringer: false
+myErrorStringer → error: true
+myErrorStringer → Stringer: true
+myReader → interface{}: true
+int → interface{}: true
+interface implements interface:
+ReadWriter → Reader: true
+ReadWriter → Writer: true
+Reader → ReadWriter: false
+Writer → ReadWriter: false
+ReadCloser → Reader: true
+ReadCloser → Closer: true
+ReadCloser → Writer: false
+Reader → ReadCloser: false
+Reader → Reader: true
+ReadWriter → ReadWriter: true
+error → Stringer: false
+Stringer → error: false
+Reader → interface{}: true
+ReadWriter → interface{}: true
+assignable to:
+int → int: true
+string → string: true
+int → string: false
+int → int64: false
+myReader → Reader: true
+*myWriter → Writer: true
+myWriter → Writer: false
+*myReadWriter → ReadWriter: true
+ReadWriter → Reader: true
+Reader → ReadWriter: false
+int → interface{}: true
+Reader → interface{}: true
+unexported method interface:
+*notAnExpr → exprLike: true
+notAnExpr → exprLike: true
+*notAnExpr → exprLike (AssignableTo): true
+channel direction:
+chan int → <-chan int: true
+<-chan int → chan int: false
+named types:
+*int → IntPtr: true
+IntPtr → *int: true
+IntPtr → IntPtr1: false
+Ch → <-chan interface{}: true
+value set interface:
+Set[0] to BarNode: 10
+Set[1] still FooNode: 2
+
 alignment / offset:
 struct{[0]func(); byte}: true
 
diff --git a/transform/interface-lowering.go b/transform/interface-lowering.go
index 7f0b6fdc57..eb954e1d03 100644
--- a/transform/interface-lowering.go
+++ b/transform/interface-lowering.go
@@ -36,6 +36,12 @@ import (
 	"tinygo.org/x/go-llvm"
 )
 
+// numMethodHasMethodSet is a flag in bit 15 of the numMethod field (uint16) in
+// Named, Pointer, and Struct type descriptors. When set, an inline method set
+// is present in the type descriptor. Must match the constant in
+// src/internal/reflectlite/type.go.
+const numMethodHasMethodSet = 0x8000
+
 // signatureInfo is a Go signature of an interface method. It does not represent
 // any method in particular.
 type signatureInfo struct {
@@ -276,7 +282,7 @@ func (p *lowerInterfacesPass) run() error {
 	for _, fn := range interfaceAssertFunctions {
 		methodsAttr := fn.GetStringAttributeAtIndex(-1, "tinygo-methods")
 		itf := p.interfaces[methodsAttr.GetStringValue()]
-		p.defineInterfaceImplementsFunc(fn, itf)
+		p.defineInterfaceAssertFunc(fn, itf)
 	}
 
 	// Replace each type assert with an actual type comparison or (if the type
@@ -325,6 +331,49 @@ func (p *lowerInterfacesPass) run() error {
 	}
 	sort.Strings(typeNames)
 
+	// Check whether runtime.typeImplementsMethodSet still has uses. Now that
+	// interface type assertions have been lowered to type-ID comparison
+	// chains, the only remaining callers would be from reflect
+	// (AssignableTo/Implements). If none remain, we can strip the inline
+	// method-set data from type descriptors to save binary size.
+	stripMethodSets := false
+	typeImplementsFn := p.mod.NamedFunction("runtime.typeImplementsMethodSet")
+	if !typeImplementsFn.IsNil() && !hasUses(typeImplementsFn) {
+		stripMethodSets = true
+	}
+
+	// Collect all method signatures that appear in any interface type
+	// descriptor. When reflect is imported and method sets are kept,
+	// concrete type method sets are pruned: individual methods not in any
+	// interface are removed, and types that can't fully satisfy at least
+	// one interface have their method sets emptied entirely.
+	//
+	// When method sets are stripped entirely (reflect not imported),
+	// methodFilter is nil and filterMethodSet replaces with empty.
+	var methodFilter map[string]struct{}
+	var ifaceMethodSets []map[string]struct{}
+	if !stripMethodSets {
+		methodFilter = make(map[string]struct{})
+		for _, name := range typeNames {
+			if !strings.HasPrefix(name, "interface:") {
+				continue
+			}
+			t := p.types[name]
+			initializer := t.typecode.Initializer()
+			ifaceSet := make(map[string]struct{})
+			for i := 0; i < initializer.Type().StructElementTypesCount(); i++ {
+				field := p.builder.CreateExtractValue(initializer, i, "")
+				for _, sig := range p.extractMethodSigs(field) {
+					methodFilter[sig] = struct{}{}
+					ifaceSet[sig] = struct{}{}
+				}
+			}
+			if len(ifaceSet) > 0 {
+				ifaceMethodSets = append(ifaceMethodSets, ifaceSet)
+			}
+		}
+	}
+
 	// Remove all method sets, which are now unnecessary and inhibit later
 	// optimizations if they are left in place.
 	zero := llvm.ConstInt(p.ctx.Int32Type(), 0, false)
@@ -332,9 +381,39 @@ func (p *lowerInterfacesPass) run() error {
 		t := p.types[name]
 		if !t.methodSet.IsNil() {
 			initializer := t.typecode.Initializer()
+			numFields := initializer.Type().StructElementTypesCount()
+
+			// Read numMethods from the original type descriptor (index 2:
+			// after prefix pointer at 0 and kind byte at 1). For Named,
+			// Pointer, and Struct types, the numMethodHasMethodSet flag
+			// indicates that an inline method set is present.
+			var numMethodsConst uint64
+			var numMethodsIsI16 bool
+			if numFields > 2 {
+				nmField := p.builder.CreateExtractValue(initializer, 2, "")
+				if nmField.Type() == p.ctx.Int16Type() {
+					numMethodsConst = nmField.ZExtValue()
+					numMethodsIsI16 = true
+				}
+			}
+
 			var newInitializerFields []llvm.Value
-			for i := 1; i < initializer.Type().StructElementTypesCount(); i++ {
-				newInitializerFields = append(newInitializerFields, p.builder.CreateExtractValue(initializer, i, ""))
+			for i := 1; i < numFields; i++ {
+				field := p.builder.CreateExtractValue(initializer, i, "")
+				field = p.filterMethodSet(field, methodFilter, ifaceMethodSets)
+				// Strip empty inline method sets for Named, Pointer, and
+				// Struct types. When the method set is pruned to empty, we
+				// remove it and clear the numMethodHasMethodSet flag (bit 15
+				// of numMethod) so the runtime skips reading it.
+				if numMethodsIsI16 && numMethodsConst&numMethodHasMethodSet != 0 && p.isMethodSetType(field.Type()) {
+					elems := field.Type().StructElementTypes()
+					if elems[1].ArrayLength() == 0 {
+						clearedNumMethods := numMethodsConst & ^uint64(numMethodHasMethodSet)
+						newInitializerFields[1] = llvm.ConstInt(p.ctx.Int16Type(), clearedNumMethods, false)
+						continue
+					}
+				}
+				newInitializerFields = append(newInitializerFields, field)
 			}
 			newInitializer := p.ctx.ConstStruct(newInitializerFields, false)
 			typecodeName := t.typecode.Name()
@@ -428,66 +507,6 @@ func (p *lowerInterfacesPass) getSignature(name string) *signatureInfo {
 	return p.signatures[name]
 }
 
-// defineInterfaceImplementsFunc defines the interface type assert function. It
-// checks whether the given interface type (passed as an argument) is one of the
-// types it implements.
-//
-// The type match is implemented using an if/else chain over all possible types.
-// This if/else chain is easily converted to a big switch over all possible
-// types by the LLVM simplifycfg pass.
-func (p *lowerInterfacesPass) defineInterfaceImplementsFunc(fn llvm.Value, itf *interfaceInfo) {
-	// Create the function and function signature.
-	fn.Param(0).SetName("actualType")
-	fn.SetLinkage(llvm.InternalLinkage)
-	fn.SetUnnamedAddr(true)
-	AddStandardAttributes(fn, p.config)
-
-	// Start the if/else chain at the entry block.
-	entry := p.ctx.AddBasicBlock(fn, "entry")
-	thenBlock := p.ctx.AddBasicBlock(fn, "then")
-	p.builder.SetInsertPointAtEnd(entry)
-
-	if p.dibuilder != nil {
-		difile := p.getDIFile("<Go interface assert>")
-		diFuncType := p.dibuilder.CreateSubroutineType(llvm.DISubroutineType{
-			File: difile,
-		})
-		difunc := p.dibuilder.CreateFunction(difile, llvm.DIFunction{
-			Name:         "(Go interface assert)",
-			File:         difile,
-			Line:         0,
-			Type:         diFuncType,
-			LocalToUnit:  true,
-			IsDefinition: true,
-			ScopeLine:    0,
-			Flags:        llvm.FlagPrototyped,
-			Optimized:    true,
-		})
-		fn.SetSubprogram(difunc)
-		p.builder.SetCurrentDebugLocation(0, 0, difunc, llvm.Metadata{})
-	}
-
-	// Iterate over all possible types.  Each iteration creates a new branch
-	// either to the 'then' block (success) or the .next block, for the next
-	// check.
-	actualType := fn.Param(0)
-	for _, typ := range itf.types {
-		nextBlock := p.ctx.AddBasicBlock(fn, typ.name+".next")
-		cmp := p.builder.CreateICmp(llvm.IntEQ, actualType, typ.typecodeGEP, typ.name+".icmp")
-		p.builder.CreateCondBr(cmp, thenBlock, nextBlock)
-		p.builder.SetInsertPointAtEnd(nextBlock)
-	}
-
-	// The builder is now inserting at the last *.next block.  Once we reach
-	// this point, all types have been checked so the type assert will have
-	// failed.
-	p.builder.CreateRet(llvm.ConstInt(p.ctx.Int1Type(), 0, false))
-
-	// Fill 'then' block (type assert was successful).
-	p.builder.SetInsertPointAtEnd(thenBlock)
-	p.builder.CreateRet(llvm.ConstInt(p.ctx.Int1Type(), 1, false))
-}
-
 // defineInterfaceMethodFunc defines this thunk by calling the concrete method
 // of the type that implements this interface.
 //
@@ -592,3 +611,171 @@ func (p *lowerInterfacesPass) getDIFile(file string) llvm.Metadata {
 	}
 	return difile
 }
+
+// defineInterfaceAssertFunc defines a $typeassert function for the given
+// interface. The function returns true if the concrete type (passed as a
+// type-ID pointer) implements the interface, using a chain of type-ID
+// comparisons. This avoids pulling in runtime.typeImplementsMethodSet for
+// programs that don't use reflect.
+func (p *lowerInterfacesPass) defineInterfaceAssertFunc(fn llvm.Value, itf *interfaceInfo) {
+	actualType := fn.FirstParam()
+	actualType.SetName("actualType")
+	fn.SetLinkage(llvm.InternalLinkage)
+	fn.SetUnnamedAddr(true)
+	AddStandardAttributes(fn, p.config)
+
+	entry := p.ctx.AddBasicBlock(fn, "entry")
+	p.builder.SetInsertPointAtEnd(entry)
+
+	if p.dibuilder != nil {
+		difile := p.getDIFile("<Go interface type assert>")
+		diFuncType := p.dibuilder.CreateSubroutineType(llvm.DISubroutineType{
+			File: difile,
+		})
+		difunc := p.dibuilder.CreateFunction(difile, llvm.DIFunction{
+			Name:         "(Go interface type assert)",
+			File:         difile,
+			Line:         0,
+			Type:         diFuncType,
+			LocalToUnit:  true,
+			IsDefinition: true,
+			ScopeLine:    0,
+			Flags:        llvm.FlagPrototyped,
+			Optimized:    true,
+		})
+		fn.SetSubprogram(difunc)
+		p.builder.SetCurrentDebugLocation(0, 0, difunc, llvm.Metadata{})
+	}
+
+	// Build an OR chain: return (type == T1) || (type == T2) || ...
+	llvmFalse := llvm.ConstInt(p.ctx.Int1Type(), 0, false)
+	result := llvmFalse
+	for _, typ := range itf.types {
+		cmp := p.builder.CreateICmp(llvm.IntEQ, actualType, typ.typecodeGEP, typ.name+".icmp")
+		result = p.builder.CreateOr(result, cmp, "")
+	}
+	p.builder.CreateRet(result)
+}
+
+// isMethodSetType reports whether ty has the shape of a method-set struct:
+// { uintptr, [N x ptr] }.
+func (p *lowerInterfacesPass) isMethodSetType(ty llvm.Type) bool {
+	if ty.TypeKind() != llvm.StructTypeKind {
+		return false
+	}
+	elems := ty.StructElementTypes()
+	if len(elems) != 2 {
+		return false
+	}
+	if elems[0] != p.uintptrType {
+		return false
+	}
+	return elems[1].TypeKind() == llvm.ArrayTypeKind && elems[1].ElementType() == p.ptrType
+}
+
+// extractMethodSigs returns the names of method signature globals inside a
+// method-set field ({ uintptr, [N x ptr] }). Returns nil if field is not a
+// method set.
+func (p *lowerInterfacesPass) extractMethodSigs(field llvm.Value) []string {
+	if !p.isMethodSetType(field.Type()) {
+		return nil
+	}
+	methodArray := p.builder.CreateExtractValue(field, 1, "")
+	n := methodArray.Type().ArrayLength()
+	sigs := make([]string, 0, n)
+	for j := 0; j < n; j++ {
+		sig := p.builder.CreateExtractValue(methodArray, j, "")
+		sig = stripPointerCasts(sig)
+		sigs = append(sigs, sig.Name())
+	}
+	return sigs
+}
+
+// filterMethodSet processes a type-descriptor field that may be a method set.
+// Non-method-set fields are returned unchanged.
+//
+// If keepSigs is nil, the method set is replaced with an empty one (strip mode,
+// used when reflect is not imported). If keepSigs is non-nil, the method set is
+// pruned in two stages: first, methods not in keepSigs (the union of all
+// interface signatures) are removed; then, if the remaining methods cannot
+// fully satisfy at least one interface in ifaceSets, the entire method set is
+// emptied.
+func (p *lowerInterfacesPass) filterMethodSet(field llvm.Value, keepSigs map[string]struct{}, ifaceSets []map[string]struct{}) llvm.Value {
+	if !p.isMethodSetType(field.Type()) {
+		return field
+	}
+
+	methodArray := p.builder.CreateExtractValue(field, 1, "")
+	numMethods := methodArray.Type().ArrayLength()
+
+	// Strip mode: replace with empty method set.
+	if keepSigs == nil {
+		return p.ctx.ConstStruct([]llvm.Value{
+			llvm.ConstInt(p.uintptrType, 0, false),
+			llvm.ConstArray(p.ptrType, nil),
+		}, false)
+	}
+
+	if numMethods == 0 {
+		return field
+	}
+
+	// Extract all methods and their signature names.
+	type methodEntry struct {
+		value llvm.Value
+		name  string
+	}
+	entries := make([]methodEntry, numMethods)
+	nameSet := make(map[string]struct{}, numMethods)
+	for j := 0; j < numMethods; j++ {
+		sig := p.builder.CreateExtractValue(methodArray, j, "")
+		stripped := stripPointerCasts(sig)
+		name := stripped.Name()
+		entries[j] = methodEntry{sig, name}
+		nameSet[name] = struct{}{}
+	}
+
+	// Check whether this type can fully implement at least one interface.
+	// If not, its method set can never produce a true result from
+	// typeImplementsMethodSet, so we can empty it entirely.
+	implementsAny := false
+	for _, ifaceSet := range ifaceSets {
+		if isSubsetOf(ifaceSet, nameSet) {
+			implementsAny = true
+			break
+		}
+	}
+	if !implementsAny {
+		return p.ctx.ConstStruct([]llvm.Value{
+			llvm.ConstInt(p.uintptrType, 0, false),
+			llvm.ConstArray(p.ptrType, nil),
+		}, false)
+	}
+
+	// Prune: keep only methods whose signature appears in keepSigs.
+	var kept []llvm.Value
+	for _, e := range entries {
+		if _, ok := keepSigs[e.name]; ok {
+			kept = append(kept, e.value)
+		}
+	}
+
+	if len(kept) == numMethods {
+		return field
+	}
+
+	return p.ctx.ConstStruct([]llvm.Value{
+		llvm.ConstInt(p.uintptrType, uint64(len(kept)), false),
+		llvm.ConstArray(p.ptrType, kept),
+	}, false)
+}
+
+// isSubsetOf reports whether every key in sub is also in super.
+func isSubsetOf(sub, super map[string]struct{}) bool {
+	for k := range sub {
+		if _, ok := super[k]; !ok {
+			return false
+		}
+	}
+	return true
+}
diff --git a/transform/optimizer.go b/transform/optimizer.go
index 1209754310..ba8d1c12e9 100644
--- a/transform/optimizer.go
+++ b/transform/optimizer.go
@@ -65,7 +65,6 @@ func Optimize(mod llvm.Module, config *compileopts.Config) []error {
 
 		// Run TinyGo-specific optimization passes.
 		OptimizeStringToBytes(mod)
-		OptimizeReflectImplements(mod)
 		maxStackSize := config.MaxStackAlloc()
 		OptimizeAllocs(mod, nil, maxStackSize, nil)
 		err = LowerInterfaces(mod, config)
diff --git a/transform/rtcalls.go b/transform/rtcalls.go
index 3abc1d3952..49b138bcc9 100644
--- a/transform/rtcalls.go
+++ b/transform/rtcalls.go
@@ -4,8 +4,6 @@ package transform
 // calls.
 
 import (
-	"strings"
-
 	"tinygo.org/x/go-llvm"
 )
 
@@ -100,81 +98,3 @@ func OptimizeStringEqual(mod llvm.Module) {
 		}
 	}
 }
-
-// OptimizeReflectImplements optimizes the following code:
-//
-//	implements := someType.Implements(someInterfaceType)
-//
-// where someType is an arbitrary reflect.Type and someInterfaceType is a
-// reflect.Type of interface kind, to the following code:
-//
-//	_, implements := someType.(interfaceType)
-//
-// if the interface type is known at compile time (that is, someInterfaceType is
-// a LLVM constant aggregate). This optimization is especially important for the
-// encoding/json package, which uses this method.
-//
-// As of this writing, the (reflect.Type).Interface method has not yet been
-// implemented so this optimization is critical for the encoding/json package.
-func OptimizeReflectImplements(mod llvm.Module) {
-	implementsSignature1 := mod.NamedGlobal("reflect/methods.Implements(reflect.Type) bool")
-	implementsSignature2 := mod.NamedGlobal("reflect/methods.Implements(internal/reflectlite.Type) bool")
-	if implementsSignature1.IsNil() && implementsSignature2.IsNil() {
-		return
-	}
-
-	builder := mod.Context().NewBuilder()
-	defer builder.Dispose()
-
-	// Look up the (reflect.Value).Implements() method.
-	var implementsFunc llvm.Value
-	for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-		attr := fn.GetStringAttributeAtIndex(-1, "tinygo-invoke")
-		if attr.IsNil() {
-			continue
-		}
-		val := attr.GetStringValue()
-		if val == "reflect/methods.Implements(reflect.Type) bool" || val == "reflect/methods.Implements(internal/reflectlite.Type) bool" {
-			implementsFunc = fn
-			break
-		}
-	}
-	if implementsFunc.IsNil() {
-		// Doesn't exist in the program, so nothing to do.
-		return
-	}
-
-	for _, call := range getUses(implementsFunc) {
-		if call.IsACallInst().IsNil() {
-			continue
-		}
-		interfaceType := stripPointerCasts(call.Operand(2))
-		if interfaceType.IsAGlobalVariable().IsNil() {
-			// Interface is unknown at compile time. This can't be optimized.
-			continue
-		}
-
-		if strings.HasPrefix(interfaceType.Name(), "reflect/types.type:named:") {
-			// Get the underlying type.
-			interfaceType = stripPointerCasts(builder.CreateExtractValue(interfaceType.Initializer(), 3, ""))
-		}
-		if !strings.HasPrefix(interfaceType.Name(), "reflect/types.type:interface:") {
-			// This is an error. The Type passed to Implements should be of
-			// interface type. Ignore it here (don't report it), it will be
-			// reported at runtime.
-			continue
-		}
-		typeAssertFunction := mod.NamedFunction(strings.TrimPrefix(interfaceType.Name(), "reflect/types.type:") + ".$typeassert")
-		if typeAssertFunction.IsNil() {
-			continue
-		}
-
-		// Replace Implements call with the type assert call.
-		builder.SetInsertPointBefore(call)
-		implements := builder.CreateCall(typeAssertFunction.GlobalValueType(), typeAssertFunction, []llvm.Value{
-			call.Operand(0), // typecode to check
-		}, "")
-		call.ReplaceAllUsesWith(implements)
-		call.EraseFromParentAsInstruction()
-	}
-}
diff --git a/transform/rtcalls_test.go b/transform/rtcalls_test.go
index 9073b0ea5b..2ae1603155 100644
--- a/transform/rtcalls_test.go
+++ b/transform/rtcalls_test.go
@@ -22,11 +22,3 @@ func TestOptimizeStringEqual(t *testing.T) {
 		transform.OptimizeStringEqual(mod)
 	})
 }
-
-func TestOptimizeReflectImplements(t *testing.T) {
-	t.Parallel()
-	testTransform(t, "testdata/reflect-implements", func(mod llvm.Module) {
-		// Run optimization pass.
-		transform.OptimizeReflectImplements(mod)
-	})
-}
diff --git a/transform/testdata/interface.ll b/transform/testdata/interface.ll
index 76ed029b47..fd2ea9a7de 100644
--- a/transform/testdata/interface.ll
+++ b/transform/testdata/interface.ll
@@ -7,7 +7,6 @@ target triple = "armv7m-none-eabi"
 @"reflect/types.typeid:basic:int16" = external constant i8
 @"reflect/types.type:basic:int" = linkonce_odr constant { i8, ptr } { i8 2, ptr @"reflect/types.type:pointer:basic:int" }, align 4
 @"reflect/types.type:pointer:basic:int" = linkonce_odr constant { i8, ptr } { i8 21, ptr @"reflect/types.type:basic:int" }, align 4
-@"reflect/methods.NeverImplementedMethod()" = linkonce_odr constant i8 0
 @"reflect/methods.Double() int" = linkonce_odr constant i8 0
 @"Number$methodset" = linkonce_odr unnamed_addr constant { i32, [1 x ptr], { ptr } } { i32 1, [1 x ptr] [ptr @"reflect/methods.Double() int"], { ptr } { ptr @"(Number).Double$invoke" } }
 @"reflect/types.type:named:Number" = linkonce_odr constant { ptr, i8, ptr, ptr } { ptr @"Number$methodset", i8 34, ptr @"reflect/types.type:pointer:named:Number", ptr @"reflect/types.type:basic:int" }, align 4
@@ -16,10 +15,7 @@ target triple = "armv7m-none-eabi"
 declare i1 @runtime.typeAssert(ptr, ptr)
 declare void @runtime.printuint8(i8)
 declare void @runtime.printint16(i16)
-declare void @runtime.printint32(i32)
-declare void @runtime.printptr(i32)
 declare void @runtime.printnl()
-declare void @runtime.nilPanic(ptr)
 
 define void @printInterfaces() {
   call void @printInterface(ptr @"reflect/types.type:basic:int", ptr inttoptr (i32 5 to ptr))
@@ -30,25 +26,6 @@ define void @printInterfaces() {
 }
 
 define void @printInterface(ptr %typecode, ptr %value) {
-  %isUnmatched = call i1 @Unmatched$typeassert(ptr %typecode)
-  br i1 %isUnmatched, label %typeswitch.Unmatched, label %typeswitch.notUnmatched
-
-typeswitch.Unmatched:
-  %unmatched = ptrtoint ptr %value to i32
-  call void @runtime.printptr(i32 %unmatched)
-  call void @runtime.printnl()
-  ret void
-
-typeswitch.notUnmatched:
-  %isDoubler = call i1 @Doubler$typeassert(ptr %typecode)
-  br i1 %isDoubler, label %typeswitch.Doubler, label %typeswitch.notDoubler
-
-typeswitch.Doubler:
-  %doubler.result = call i32 @"Doubler.Double$invoke"(ptr %value, ptr %typecode, ptr undef)
-  call void @runtime.printint32(i32 %doubler.result)
-  ret void
-
-typeswitch.notDoubler:
   %isByte = call i1 @runtime.typeAssert(ptr %typecode, ptr nonnull @"reflect/types.typeid:basic:uint8")
   br i1 %isByte, label %typeswitch.byte, label %typeswitch.notByte
 
@@ -86,10 +63,4 @@ define i32 @"(Number).Double$invoke"(ptr %receiverPtr, ptr %context) {
 
 declare i32 @"Doubler.Double$invoke"(ptr %receiver, ptr %typecode, ptr %context) #0
 
-declare i1 @Doubler$typeassert(ptr %typecode) #1
-
-declare i1 @Unmatched$typeassert(ptr %typecode) #2
-
 attributes #0 = { "tinygo-invoke"="reflect/methods.Double() int" "tinygo-methods"="reflect/methods.Double() int" }
-attributes #1 = { "tinygo-methods"="reflect/methods.Double() int" }
-attributes #2 = { "tinygo-methods"="reflect/methods.NeverImplementedMethod()" }
diff --git a/transform/testdata/interface.out.ll b/transform/testdata/interface.out.ll
index cb041ab1db..bbbc5d9245 100644
--- a/transform/testdata/interface.out.ll
+++ b/transform/testdata/interface.out.ll
@@ -12,14 +12,8 @@ declare void @runtime.printuint8(i8)
 
 declare void @runtime.printint16(i16)
 
-declare void @runtime.printint32(i32)
-
-declare void @runtime.printptr(i32)
-
 declare void @runtime.printnl()
 
-declare void @runtime.nilPanic(ptr)
-
 define void @printInterfaces() {
   call void @printInterface(ptr @"reflect/types.type:basic:int", ptr inttoptr (i32 5 to ptr))
   call void @printInterface(ptr @"reflect/types.type:basic:uint8", ptr inttoptr (i8 120 to ptr))
@@ -28,35 +22,16 @@ define void @printInterfaces() {
 }
 
 define void @printInterface(ptr %typecode, ptr %value) {
-  %isUnmatched = call i1 @"Unmatched$typeassert"(ptr %typecode)
-  br i1 %isUnmatched, label %typeswitch.Unmatched, label %typeswitch.notUnmatched
-
-typeswitch.Unmatched:                             ; preds = %0
-  %unmatched = ptrtoint ptr %value to i32
-  call void @runtime.printptr(i32 %unmatched)
-  call void @runtime.printnl()
-  ret void
-
-typeswitch.notUnmatched:                          ; preds = %0
-  %isDoubler = call i1 @"Doubler$typeassert"(ptr %typecode)
-  br i1 %isDoubler, label %typeswitch.Doubler, label %typeswitch.notDoubler
-
-typeswitch.Doubler:                               ; preds = %typeswitch.notUnmatched
-  %doubler.result = call i32 @"Doubler.Double$invoke"(ptr %value, ptr %typecode, ptr undef)
-  call void @runtime.printint32(i32 %doubler.result)
-  ret void
-
-typeswitch.notDoubler:                            ; preds = %typeswitch.notUnmatched
   %typeassert.ok = icmp eq ptr @"reflect/types.type:basic:uint8", %typecode
   br i1 %typeassert.ok, label %typeswitch.byte, label %typeswitch.notByte
 
-typeswitch.byte:                                  ; preds = %typeswitch.notDoubler
+typeswitch.byte:                                  ; preds = %0
   %byte = ptrtoint ptr %value to i8
   call void @runtime.printuint8(i8 %byte)
   call void @runtime.printnl()
   ret void
 
-typeswitch.notByte:                               ; preds = %typeswitch.notDoubler
+typeswitch.notByte:                               ; preds = %0
   br i1 false, label %typeswitch.int16, label %typeswitch.notInt16
 
 typeswitch.int16:                                 ; preds = %typeswitch.notByte
@@ -79,41 +54,3 @@ define i32 @"(Number).Double$invoke"(ptr %receiverPtr, ptr %context) {
   %ret = call i32 @"(Number).Double"(i32 %receiver, ptr undef)
   ret i32 %ret
 }
-
-define internal i32 @"Doubler.Double$invoke"(ptr %receiver, ptr %actualType, ptr %context) unnamed_addr #0 {
-entry:
-  %"named:Number.icmp" = icmp eq ptr %actualType, @"reflect/types.type:named:Number"
-  br i1 %"named:Number.icmp", label %"named:Number", label %"named:Number.next"
-
-"named:Number":                                   ; preds = %entry
-  %0 = call i32 @"(Number).Double$invoke"(ptr %receiver, ptr undef)
-  ret i32 %0
-
-"named:Number.next":                              ; preds = %entry
-  call void @runtime.nilPanic(ptr undef)
-  unreachable
-}
-
-define internal i1 @"Doubler$typeassert"(ptr %actualType) unnamed_addr #1 {
-entry:
-  %"named:Number.icmp" = icmp eq ptr %actualType, @"reflect/types.type:named:Number"
-  br i1 %"named:Number.icmp", label %then, label %"named:Number.next"
-
-then:                                             ; preds = %entry
-  ret i1 true
-
-"named:Number.next":                              ; preds = %entry
-  ret i1 false
-}
-
-define internal i1 @"Unmatched$typeassert"(ptr %actualType) unnamed_addr #2 {
-entry:
-  ret i1 false
-
-then:                                             ; No predecessors!
-  ret i1 true
-}
-
-attributes #0 = { "tinygo-invoke"="reflect/methods.Double() int" "tinygo-methods"="reflect/methods.Double() int" }
-attributes #1 = { "tinygo-methods"="reflect/methods.Double() int" }
-attributes #2 = { "tinygo-methods"="reflect/methods.NeverImplementedMethod()" }
diff --git a/transform/testdata/reflect-implements.ll b/transform/testdata/reflect-implements.ll
deleted file mode 100644
index 46536483b2..0000000000
--- a/transform/testdata/reflect-implements.ll
+++ /dev/null
@@ -1,41 +0,0 @@
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-%runtime._interface = type { ptr, ptr }
-
-@"reflect/types.type:named:error" = internal constant { i8, i16, ptr, ptr } { i8 52, i16 0, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:interface:{Error:func:{}{basic:string}}" = internal constant { i8, ptr } { i8 20, ptr @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = internal constant { i8, ptr } { i8 21, ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:pointer:named:error" = internal constant { i8, i16, ptr } { i8 21, i16 0, ptr @"reflect/types.type:named:error" }, align 4
-@"reflect/types.type:pointer:named:reflect.rawType" = internal constant { ptr, i8, i16, ptr } { ptr null, i8 21, i16 0, ptr null }, align 4
-@"reflect/methods.Implements(reflect.Type) bool" = internal constant i8 0, align 1
-
-; var errorType = reflect.TypeOf((*error)(nil)).Elem()
-; func isError(typ reflect.Type) bool {
-;   return typ.Implements(errorType)
-; }
-; The type itself is stored in %typ.value, %typ.typecode just refers to the
-; type of reflect.Type. This function can be optimized because errorType is
-; known at compile time (after the interp pass has run).
-define i1 @main.isError(ptr %typ.typecode, ptr %typ.value, ptr %context) {
-entry:
-  %result = call i1 @"reflect.Type.Implements$invoke"(ptr %typ.value, ptr getelementptr inbounds ({ ptr, i8, ptr }, ptr @"reflect/types.type:pointer:named:reflect.rawType", i32 0, i32 1), ptr @"reflect/types.type:named:error", ptr %typ.typecode, ptr undef)
-  ret i1 %result
-}
-
-; This Implements method call can not be optimized because itf is not known at
-; compile time.
-; func isUnknown(typ, itf reflect.Type) bool {
-;   return typ.Implements(itf)
-; }
-define i1 @main.isUnknown(ptr %typ.typecode, ptr %typ.value, ptr %itf.typecode, ptr %itf.value, ptr %context) {
-entry:
-  %result = call i1 @"reflect.Type.Implements$invoke"(ptr %typ.value, ptr %itf.typecode, ptr %itf.value, ptr %typ.typecode, ptr undef)
-  ret i1 %result
-}
-
-declare i1 @"reflect.Type.Implements$invoke"(ptr, ptr, ptr, ptr, ptr) #0
-declare i1 @"interface:{Error:func:{}{basic:string}}.$typeassert"(ptr %0) #1
-
-attributes #0 = { "tinygo-invoke"="reflect/methods.Implements(reflect.Type) bool" "tinygo-methods"="reflect/methods.Align() int; reflect/methods.Implements(reflect.Type) bool" }
-attributes #1 = { "tinygo-methods"="reflect/methods.Error() string" }
diff --git a/transform/testdata/reflect-implements.out.ll b/transform/testdata/reflect-implements.out.ll
deleted file mode 100644
index b7b759c018..0000000000
--- a/transform/testdata/reflect-implements.out.ll
+++ /dev/null
@@ -1,28 +0,0 @@
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-@"reflect/types.type:named:error" = internal constant { i8, i16, ptr, ptr } { i8 52, i16 0, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:interface:{Error:func:{}{basic:string}}" = internal constant { i8, ptr } { i8 20, ptr @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = internal constant { i8, ptr } { i8 21, ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4
-@"reflect/types.type:pointer:named:error" = internal constant { i8, i16, ptr } { i8 21, i16 0, ptr @"reflect/types.type:named:error" }, align 4
-@"reflect/types.type:pointer:named:reflect.rawType" = internal constant { ptr, i8, i16, ptr } { ptr null, i8 21, i16 0, ptr null }, align 4
-@"reflect/methods.Implements(reflect.Type) bool" = internal constant i8 0, align 1
-
-define i1 @main.isError(ptr %typ.typecode, ptr %typ.value, ptr %context) {
-entry:
-  %0 = call i1 @"interface:{Error:func:{}{basic:string}}.$typeassert"(ptr %typ.value)
-  ret i1 %0
-}
-
-define i1 @main.isUnknown(ptr %typ.typecode, ptr %typ.value, ptr %itf.typecode, ptr %itf.value, ptr %context) {
-entry:
-  %result = call i1 @"reflect.Type.Implements$invoke"(ptr %typ.value, ptr %itf.typecode, ptr %itf.value, ptr %typ.typecode, ptr undef)
-  ret i1 %result
-}
-
-declare i1 @"reflect.Type.Implements$invoke"(ptr, ptr, ptr, ptr, ptr) #0
-
-declare i1 @"interface:{Error:func:{}{basic:string}}.$typeassert"(ptr) #1
-
-attributes #0 = { "tinygo-invoke"="reflect/methods.Implements(reflect.Type) bool" "tinygo-methods"="reflect/methods.Align() int; reflect/methods.Implements(reflect.Type) bool" }
-attributes #1 = { "tinygo-methods"="reflect/methods.Error() string" }