3 files changed, 32 insertions, 7 deletions
diff --git a/src/cmd/go/internal/load/flag.go b/src/cmd/go/internal/load/flag.go
index 4e0cb5bc19..24670524fc 100644
--- a/src/cmd/go/internal/load/flag.go
+++ b/src/cmd/go/internal/load/flag.go
@@ -22,8 +22,9 @@ var (
 // that allows specifying different effective flags for different packages.
 // See 'go help build' for more details about per-package flags.
 type PerPackageFlag struct {
-	present bool
-	values  []ppfValue
+	present      bool
+	values       []ppfValue
+	seenPackages map[*Package]bool // the packages for which the flags have already been set
 }
 
 // A ppfValue is a single <pattern>=<flags> per-package flag value.
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 4013330bc4..317053d918 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -2630,10 +2630,20 @@ func (e *mainPackageError) ImportPath() string {
 
 func setToolFlags(pkgs ...*Package) {
 	for _, p := range PackageList(pkgs) {
-		p.Internal.Asmflags = BuildAsmflags.For(p)
-		p.Internal.Gcflags = BuildGcflags.For(p)
-		p.Internal.Ldflags = BuildLdflags.For(p)
-		p.Internal.Gccgoflags = BuildGccgoflags.For(p)
+		appendFlags(p, &p.Internal.Asmflags, &BuildAsmflags)
+		appendFlags(p, &p.Internal.Gcflags, &BuildGcflags)
+		appendFlags(p, &p.Internal.Ldflags, &BuildLdflags)
+		appendFlags(p, &p.Internal.Gccgoflags, &BuildGccgoflags)
+	}
+}
+
+func appendFlags(p *Package, flags *[]string, packageFlag *PerPackageFlag) {
+	if !packageFlag.seenPackages[p] {
+		if packageFlag.seenPackages == nil {
+			packageFlag.seenPackages = make(map[*Package]bool)
+		}
+		packageFlag.seenPackages[p] = true
+		*flags = append(*flags, packageFlag.For(p)...)
 	}
 }
 
diff --git a/src/cmd/go/internal/load/test.go b/src/cmd/go/internal/load/test.go
index 42eefe37ba..da6d1cb21d 100644
--- a/src/cmd/go/internal/load/test.go
+++ b/src/cmd/go/internal/load/test.go
@@ -555,6 +555,7 @@ func formatTestmain(t *testFuncs) ([]byte, error) {
 type testFuncs struct {
 	Tests       []testFunc
 	Benchmarks  []testFunc
+	FuzzTargets []testFunc
 	Examples    []testFunc
 	TestMain    *testFunc
 	Package     *Package
@@ -653,6 +654,13 @@ func (t *testFuncs) load(filename, pkg string, doImport, seen *bool) error {
 			}
 			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, "", false})
 			*doImport, *seen = true, true
+		case isTest(name, "Fuzz"):
+			err := checkTestFunc(n, "F")
+			if err != nil {
+				return err
+			}
+			t.FuzzTargets = append(t.FuzzTargets, testFunc{pkg, name, "", false})
+			*doImport, *seen = true, true
 		}
 	}
 	ex := doc.Examples(f)
@@ -716,6 +724,12 @@ var benchmarks = []testing.InternalBenchmark{
 {{end}}
 }
 
+var fuzzTargets = []testing.InternalFuzzTarget{
+{{range .FuzzTargets}}
+	{"{{.Name}}", {{.Package}}.{{.Name}}},
+{{end}}
+}
+
 var examples = []testing.InternalExample{
 {{range .Examples}}
 	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}, {{.Unordered}}},
@@ -774,7 +788,7 @@ func main() {
 		CoveredPackages: {{printf "%q" .Covered}},
 	})
 {{end}}
-	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, examples)
+	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, fuzzTargets, examples)
 {{with .TestMain}}
 	{{.Package}}.{{.Name}}(m)
 	os.Exit(int(reflect.ValueOf(m).Elem().FieldByName("exitCode").Int()))