diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index 6734d53d5b2..e470cacda81 100644
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -425,6 +425,16 @@ func runBuild(cmd *Command, args []string) {
 	if buildBuildmode == "shared" {
 		a = b.libaction(libname(args))
 		mode = depMode
+
+		// Currently build mode shared forces external linking
+		// mode, and external linking mode forces an import of
+		// runtime/cgo.
+		var stk importStack
+		p := loadPackage("runtime/cgo", &stk)
+		if p.Error != nil {
+			fatalf("load runtime/cgo: %v", p.Error)
+		}
+		a.deps = append(a.deps, b.action(mode, depMode, p))
 	} else {
 		a = &action{}
 	}
diff --git a/src/cmd/go/pkg.go b/src/cmd/go/pkg.go
index 8bf0f568f79..11986ccfbf6 100644
--- a/src/cmd/go/pkg.go
+++ b/src/cmd/go/pkg.go
@@ -534,6 +534,14 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	if len(p.CgoFiles) > 0 && (!p.Standard || !cgoSyscallExclude[p.ImportPath]) {
 		importPaths = append(importPaths, "syscall")
 	}
+
+	// Currently build mode c-shared, or -linkshared, forces
+	// external linking mode, and external linking mode forces an
+	// import of runtime/cgo.
+	if p.Name == "main" && !p.Goroot && (buildBuildmode == "c-shared" || buildLinkshared) {
+		importPaths = append(importPaths, "runtime/cgo")
+	}
+
 	// Everything depends on runtime, except runtime and unsafe.
 	if !p.Standard || (p.ImportPath != "runtime" && p.ImportPath != "unsafe") {
 		importPaths = append(importPaths, "runtime")