diff --git a/misc/cgo/testshared/shared_test.go b/misc/cgo/testshared/shared_test.go
index a296005780..846a27173e 100644
--- a/misc/cgo/testshared/shared_test.go
+++ b/misc/cgo/testshared/shared_test.go
@@ -905,3 +905,9 @@ func TestGlobal(t *testing.T) {
 	AssertIsLinkedTo(t, "./bin/global", soname)
 	AssertHasRPath(t, "./bin/global", gorootInstallDir)
 }
+
+// Run a test using -linkshared of an installed shared package.
+// Issue 26400.
+func TestTestInstalledShared(t *testing.T) {
+	goCmd(nil, "test", "-linkshared", "-test.short", "sync/atomic")
+}
diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go
index 9cbc89f32b..e26f8655fa 100644
--- a/src/cmd/go/internal/work/action.go
+++ b/src/cmd/go/internal/work/action.go
@@ -407,7 +407,16 @@ func (b *Builder) vetAction(mode, depMode BuildMode, p *load.Package) *Action {
 		stk.Pop()
 		aFmt := b.CompileAction(ModeBuild, depMode, p1)
 
-		deps := []*Action{a1, aFmt}
+		var deps []*Action
+		if a1.buggyInstall {
+			// (*Builder).vet expects deps[0] to be the package
+			// and deps[1] to be "fmt". If we see buggyInstall
+			// here then a1 is an install of a shared library,
+			// and the real package is a1.Deps[0].
+			deps = []*Action{a1.Deps[0], aFmt, a1}
+		} else {
+			deps = []*Action{a1, aFmt}
+		}
 		for _, p1 := range load.PackageList(p.Internal.Imports) {
 			deps = append(deps, b.vetAction(mode, depMode, p1))
 		}
@@ -424,7 +433,7 @@ func (b *Builder) vetAction(mode, depMode BuildMode, p *load.Package) *Action {
 			// Built-in packages like unsafe.
 			return a
 		}
-		a1.needVet = true
+		deps[0].needVet = true
 		a.Func = (*Builder).vet
 		return a
 	})
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 514d9c3867..e00b528522 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -1368,7 +1368,9 @@ func BuildInstallFunc(b *Builder, a *Action) (err error) {
 	// so the built target is not in the a1.Objdir tree that b.cleanup(a1) removes.
 	if a1.built == a.Target {
 		a.built = a.Target
-		b.cleanup(a1)
+		if !a.buggyInstall {
+			b.cleanup(a1)
+		}
 		// Whether we're smart enough to avoid a complete rebuild
 		// depends on exactly what the staleness and rebuild algorithms
 		// are, as well as potentially the state of the Go build cache.
@@ -1422,7 +1424,9 @@ func BuildInstallFunc(b *Builder, a *Action) (err error) {
 		}
 	}
 
-	defer b.cleanup(a1)
+	if !a.buggyInstall {
+		defer b.cleanup(a1)
+	}
 
 	return b.moveOrCopyFile(a.Target, a1.built, perm, false)
 }