diff --git a/misc/cgo/testgodefs/test.bash b/misc/cgo/testgodefs/test.bash
index 14235c05cb4..a82ff9328fe 100755
--- a/misc/cgo/testgodefs/test.bash
+++ b/misc/cgo/testgodefs/test.bash
@@ -12,7 +12,7 @@ FILE_PREFIXES="anonunion issue8478"
 RM=
 for FP in $FILE_PREFIXES
 do
-  go tool cgo -godefs ${FP}.go > ${FP}_defs.go
+  go tool cgo -godefs -srcdir . ${FP}.go > ${FP}_defs.go
   RM="${RM} ${FP}_defs.go"
 done
 
diff --git a/src/cmd/cgo/doc.go b/src/cmd/cgo/doc.go
index e5d288167ec..85441e61c04 100644
--- a/src/cmd/cgo/doc.go
+++ b/src/cmd/cgo/doc.go
@@ -326,6 +326,9 @@ The following options are available when running cgo directly:
 		Write out input file in Go syntax replacing C package
 		names with real values. Used to generate files in the
 		syscall package when bootstrapping a new target.
+	-srcdir directory
+		Find the Go input files, listed on the command line,
+		in directory.
 	-objdir directory
 		Put all generated files in directory.
 	-importpath string
diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index 52cffd6520c..77b45a5aed7 100644
--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -178,6 +178,7 @@ var dynlinker = flag.Bool("dynlinker", false, "record dynamic linker information
 // constant values used in the host's C libraries and system calls.
 var godefs = flag.Bool("godefs", false, "for bootstrap: write Go definitions for C file to standard output")
 
+var srcDir = flag.String("srcdir", "", "source directory")
 var objDir = flag.String("objdir", "", "object directory")
 var importPath = flag.String("importpath", "", "import path of package being built (for comments in generated files)")
 var exportHeader = flag.String("exportheader", "", "where to write export header if any exported functions")
@@ -256,6 +257,9 @@ func main() {
 	// Use the beginning of the md5 of the input to disambiguate.
 	h := md5.New()
 	for _, input := range goFiles {
+		if *srcDir != "" {
+			input = filepath.Join(*srcDir, input)
+		}
 		f, err := os.Open(input)
 		if err != nil {
 			fatalf("%s", err)
@@ -267,6 +271,9 @@ func main() {
 
 	fs := make([]*File, len(goFiles))
 	for i, input := range goFiles {
+		if *srcDir != "" {
+			input = filepath.Join(*srcDir, input)
+		}
 		f := new(File)
 		f.ReadGo(input)
 		f.DiscardCgoDirectives()