Index: irgen/runtime.go
===================================================================
--- irgen/runtime.go
+++ irgen/runtime.go
@@ -64,6 +64,7 @@
 	// Runtime intrinsics
 	append,
 	assertInterface,
+	byteArrayToString,
 	canRecover,
 	chanCap,
 	chanLen,
@@ -92,7 +93,6 @@
 	New,
 	newChannel,
 	newMap,
-	NewNopointers,
 	newSelect,
 	panic,
 	printBool,
@@ -121,6 +121,7 @@
 	stringiter2,
 	stringPlus,
 	stringSlice,
+	stringToByteArray,
 	stringToIntArray,
 	typeDescriptorsEqual,
 	undefer runtimeFnInfo
@@ -141,6 +142,7 @@
 	UnsafePointer := types.Typ[types.UnsafePointer]
 
 	EmptyInterface := types.NewInterface(nil, nil)
+	ByteSlice := types.NewSlice(types.Typ[types.Byte])
 	IntSlice := types.NewSlice(types.Typ[types.Int])
 
 	for _, rt := range [...]struct {
@@ -245,6 +247,12 @@
 			res:  []types.Type{EmptyInterface, Bool},
 		},
 		{
+			name: "__go_byte_array_to_string",
+			rfi:  &ri.byteArrayToString,
+			args: []types.Type{UnsafePointer, Int},
+			res:  []types.Type{String},
+		},
+		{
 			name: "__go_int_array_to_string",
 			rfi:  &ri.intArrayToString,
 			args: []types.Type{UnsafePointer, Int},
@@ -319,12 +327,6 @@
 			res:  []types.Type{UnsafePointer},
 		},
 		{
-			name: "__go_new_nopointers",
-			rfi:  &ri.NewNopointers,
-			args: []types.Type{UnsafePointer, Uintptr},
-			res:  []types.Type{UnsafePointer},
-		},
-		{
 			name: "runtime.newselect",
 			rfi:  &ri.newSelect,
 			args: []types.Type{Int32},
@@ -466,6 +468,12 @@
 			res:  []types.Type{String},
 		},
 		{
+			name: "__go_string_to_byte_array",
+			rfi:  &ri.stringToByteArray,
+			args: []types.Type{String},
+			res:  []types.Type{ByteSlice},
+		},
+		{
 			name: "__go_string_to_int_array",
 			rfi:  &ri.stringToIntArray,
 			args: []types.Type{String},
@@ -563,12 +571,6 @@
 	return v
 }
 
-func (fr *frame) createMalloc(size llvm.Value) llvm.Value {
-	return fr.runtime.NewNopointers.callOnly(fr,
-		llvm.ConstNull(llvm.PointerType(llvm.Int8Type(), 0)),
-		fr.createZExtOrTrunc(size, fr.target.IntPtrType(), ""))[0]
-}
-
 func (fr *frame) createTypeMalloc(t types.Type) llvm.Value {
 	size := llvm.ConstInt(fr.target.IntPtrType(), uint64(fr.llvmtypes.Sizeof(t)), false)
 	malloc := fr.runtime.New.callOnly(fr, fr.types.ToRuntime(t), size)[0]
Index: irgen/value.go
===================================================================
--- irgen/value.go
+++ irgen/value.go
@@ -17,6 +17,7 @@
 import (
 	"fmt"
 	"go/token"
+
 	"llvm.org/llgo/third_party/gotools/go/exact"
 	"llvm.org/llgo/third_party/gotools/go/types"
 	"llvm.org/llvm/bindings/go/llvm"
@@ -480,20 +481,8 @@
 
 		// string -> []byte
 		if isSlice(dsttyp, types.Byte) {
-			value := v.value
-			strdata := fr.builder.CreateExtractValue(value, 0, "")
-			strlen := fr.builder.CreateExtractValue(value, 1, "")
-
-			// Data must be copied, to prevent changes in
-			// the byte slice from mutating the string.
-			newdata := fr.createMalloc(strlen)
-			fr.memcpy(newdata, strdata, strlen)
-
-			struct_ := llvm.Undef(fr.types.ToLLVM(dsttyp))
-			struct_ = fr.builder.CreateInsertValue(struct_, newdata, 0, "")
-			struct_ = fr.builder.CreateInsertValue(struct_, strlen, 1, "")
-			struct_ = fr.builder.CreateInsertValue(struct_, strlen, 2, "")
-			return newValue(struct_, origdsttyp)
+			sliceValue := fr.runtime.stringToByteArray.callOnly(fr, v.value)[0]
+			return newValue(sliceValue, origdsttyp)
 		}
 
 		// string -> []rune
@@ -504,19 +493,10 @@
 
 	// []byte -> string
 	if isSlice(srctyp, types.Byte) && isString(dsttyp) {
-		value := v.value
-		data := fr.builder.CreateExtractValue(value, 0, "")
-		len := fr.builder.CreateExtractValue(value, 1, "")
-
-		// Data must be copied, to prevent changes in
-		// the byte slice from mutating the string.
-		newdata := fr.createMalloc(len)
-		fr.memcpy(newdata, data, len)
-
-		struct_ := llvm.Undef(fr.types.ToLLVM(types.Typ[types.String]))
-		struct_ = fr.builder.CreateInsertValue(struct_, newdata, 0, "")
-		struct_ = fr.builder.CreateInsertValue(struct_, len, 1, "")
-		return newValue(struct_, types.Typ[types.String])
+		data := fr.builder.CreateExtractValue(v.value, 0, "")
+		len := fr.builder.CreateExtractValue(v.value, 1, "")
+		stringValue := fr.runtime.byteArrayToString.callOnly(fr, data, len)[0]
+		return newValue(stringValue, dsttyp)
 	}
 
 	// []rune -> string