diff --git a/src/cmd/go/internal/load/icfg.go b/src/cmd/go/internal/load/icfg.go
deleted file mode 100644
index d8dd66426b..0000000000
--- a/src/cmd/go/internal/load/icfg.go
+++ /dev/null
@@ -1,78 +0,0 @@
-// Copyright 2017 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package load
-
-import (
-	"bytes"
-	"encoding/json"
-	"errors"
-	"io/ioutil"
-)
-
-// DebugDeprecatedImportcfg is installed as the undocumented -debug-deprecated-importcfg build flag.
-// It is useful for debugging subtle problems in the go command logic but not something
-// we want users to depend on. The hope is that the "deprecated" will make that clear.
-// We intend to remove this flag in Go 1.11.
-var DebugDeprecatedImportcfg debugDeprecatedImportcfgFlag
-
-type debugDeprecatedImportcfgFlag struct {
-	enabled bool
-	Import  map[string]string
-	Pkg     map[string]*debugDeprecatedImportcfgPkg
-}
-
-type debugDeprecatedImportcfgPkg struct {
-	Dir    string
-	Import map[string]string
-}
-
-var (
-	debugDeprecatedImportcfgMagic = []byte("# debug-deprecated-importcfg\n")
-	errImportcfgSyntax            = errors.New("malformed syntax")
-)
-
-func (f *debugDeprecatedImportcfgFlag) String() string { return "" }
-
-func (f *debugDeprecatedImportcfgFlag) Set(x string) error {
-	if x == "" {
-		*f = debugDeprecatedImportcfgFlag{}
-		return nil
-	}
-	data, err := ioutil.ReadFile(x)
-	if err != nil {
-		return err
-	}
-
-	if !bytes.HasPrefix(data, debugDeprecatedImportcfgMagic) {
-		return errImportcfgSyntax
-	}
-	data = data[len(debugDeprecatedImportcfgMagic):]
-
-	f.Import = nil
-	f.Pkg = nil
-	if err := json.Unmarshal(data, &f); err != nil {
-		return errImportcfgSyntax
-	}
-	f.enabled = true
-	return nil
-}
-
-func (f *debugDeprecatedImportcfgFlag) lookup(parent *Package, path string) (dir, newPath string) {
-	newPath = path
-	if p := f.Import[path]; p != "" {
-		newPath = p
-	}
-	if parent != nil {
-		if p1 := f.Pkg[parent.ImportPath]; p1 != nil {
-			if p := p1.Import[path]; p != "" {
-				newPath = p
-			}
-		}
-	}
-	if p2 := f.Pkg[newPath]; p2 != nil {
-		return p2.Dir, newPath
-	}
-	return "", ""
-}
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index e496ce90f0..b81b4e98dc 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -423,14 +423,8 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
 	importPath := path
 	origPath := path
 	isLocal := build.IsLocalImport(path)
-	var debugDeprecatedImportcfgDir string
 	if isLocal {
 		importPath = dirToImportPath(filepath.Join(srcDir, path))
-	} else if DebugDeprecatedImportcfg.enabled {
-		if d, i := DebugDeprecatedImportcfg.lookup(parent, path); d != "" {
-			debugDeprecatedImportcfgDir = d
-			importPath = i
-		}
 	} else if mode&UseVendor != 0 {
 		// We do our own vendor resolution, because we want to
 		// find out the key to use in packageCache without the
@@ -452,26 +446,17 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
 		// Load package.
 		// Import always returns bp != nil, even if an error occurs,
 		// in order to return partial information.
-		var bp *build.Package
-		var err error
-		if debugDeprecatedImportcfgDir != "" {
-			bp, err = cfg.BuildContext.ImportDir(debugDeprecatedImportcfgDir, 0)
-		} else if DebugDeprecatedImportcfg.enabled {
-			bp = new(build.Package)
-			err = fmt.Errorf("unknown import path %q: not in import cfg", importPath)
-		} else {
-			buildMode := build.ImportComment
-			if mode&UseVendor == 0 || path != origPath {
-				// Not vendoring, or we already found the vendored path.
-				buildMode |= build.IgnoreVendor
-			}
-			bp, err = cfg.BuildContext.Import(path, srcDir, buildMode)
+		buildMode := build.ImportComment
+		if mode&UseVendor == 0 || path != origPath {
+			// Not vendoring, or we already found the vendored path.
+			buildMode |= build.IgnoreVendor
 		}
+		bp, err := cfg.BuildContext.Import(path, srcDir, buildMode)
 		bp.ImportPath = importPath
 		if cfg.GOBIN != "" {
 			bp.BinDir = cfg.GOBIN
 		}
-		if debugDeprecatedImportcfgDir == "" && err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path &&
+		if err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path &&
 			!strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/") {
 			err = fmt.Errorf("code in directory %s expects import %q", bp.Dir, bp.ImportComment)
 		}
@@ -480,7 +465,7 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
 			p = setErrorPos(p, importPos)
 		}
 
-		if debugDeprecatedImportcfgDir == "" && origPath != cleanImport(origPath) {
+		if origPath != cleanImport(origPath) {
 			p.Error = &PackageError{
 				ImportStack: stk.Copy(),
 				Err:         fmt.Sprintf("non-canonical import path: %q should be %q", origPath, pathpkg.Clean(origPath)),
@@ -557,13 +542,6 @@ func isDir(path string) bool {
 // x/vendor/path, vendor/path, or else stay path if none of those exist.
 // VendoredImportPath returns the expanded path or, if no expansion is found, the original.
 func VendoredImportPath(parent *Package, path string) (found string) {
-	if DebugDeprecatedImportcfg.enabled {
-		if d, i := DebugDeprecatedImportcfg.lookup(parent, path); d != "" {
-			return i
-		}
-		return path
-	}
-
 	if parent == nil || parent.Root == "" {
 		return path
 	}
diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index 86972cb61b..e5f0e624c3 100644
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -229,7 +229,6 @@ func AddBuildFlags(cmd *base.Command) {
 
 	// Undocumented, unstable debugging flags.
 	cmd.Flag.StringVar(&cfg.DebugActiongraph, "debug-actiongraph", "", "")
-	cmd.Flag.Var(&load.DebugDeprecatedImportcfg, "debug-deprecated-importcfg", "")
 }
 
 // fileExtSplit expects a filename and returns the name