diff --git a/mockgen/deprecated.go b/mockgen/deprecated.go
index ee7fa21..0b45a2e 100644
--- a/mockgen/deprecated.go
+++ b/mockgen/deprecated.go
@@ -7,15 +7,13 @@ import (
 )
 
 const (
-	deprecatedFlagProgOnly   = "prog_only"
-	deprecatedFlagExecOnly   = "exec_only"
-	deprecatedFlagBuildFlags = "build_flags"
+	deprecatedFlagProgOnly = "prog_only"
+	deprecatedFlagExecOnly = "exec_only"
 )
 
 var (
 	_ = flag.Bool("prog_only", false, "DEPRECATED (reflect mode) Only generate the reflection program; write it to stdout and exit.")
 	_ = flag.String("exec_only", "", "DEPRECATED (reflect mode) If set, execute this reflection program.")
-	_ = flag.String("build_flags", "", "DEPRECATED (reflect mode) Additional flags for go build.")
 )
 
 // notifyAboutDeprecatedFlags prints a warning message for a deprecated flags if they are set.
@@ -29,8 +27,6 @@ func notifyAboutDeprecatedFlags() {
 			logger.Println("The -prog_only flag is deprecated and has no effect.", resetColorPostfix)
 		case deprecatedFlagExecOnly:
 			logger.Println("The -exec_only flag is deprecated and has no effect.", resetColorPostfix)
-		case deprecatedFlagBuildFlags:
-			logger.Println("The -build_flags flag is deprecated and has no effect.", resetColorPostfix)
 		}
 	})
 }
diff --git a/mockgen/internal/tests/build_flags/directive.go b/mockgen/internal/tests/build_flags/directive.go
new file mode 100644
index 0000000..4bfc9e9
--- /dev/null
+++ b/mockgen/internal/tests/build_flags/directive.go
@@ -0,0 +1,6 @@
+package build_flags
+
+// one build flag
+//go:generate mockgen -destination=mock1/interfaces_mock.go -build_flags=-tags=tag1 . Interface
+// multiple build flags
+//go:generate mockgen -destination=mock2/interfaces_mock.go "-build_flags=-race -tags=tag2" . Interface
diff --git a/mockgen/internal/tests/build_flags/interfaces_1.go b/mockgen/internal/tests/build_flags/interfaces_1.go
new file mode 100644
index 0000000..e159cd6
--- /dev/null
+++ b/mockgen/internal/tests/build_flags/interfaces_1.go
@@ -0,0 +1,7 @@
+//go:build tag1
+
+package build_flags
+
+type Interface interface {
+	HelloWorld() string
+}
diff --git a/mockgen/internal/tests/build_flags/interfaces_2.go b/mockgen/internal/tests/build_flags/interfaces_2.go
new file mode 100644
index 0000000..5404cf7
--- /dev/null
+++ b/mockgen/internal/tests/build_flags/interfaces_2.go
@@ -0,0 +1,7 @@
+//go:build tag2
+
+package build_flags
+
+type Interface interface {
+	Foo()
+}
diff --git a/mockgen/internal/tests/build_flags/mock1/interfaces_mock.go b/mockgen/internal/tests/build_flags/mock1/interfaces_mock.go
new file mode 100644
index 0000000..7ca80bd
--- /dev/null
+++ b/mockgen/internal/tests/build_flags/mock1/interfaces_mock.go
@@ -0,0 +1,54 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: go.uber.org/mock/mockgen/internal/tests/build_flags (interfaces: Interface)
+//
+// Generated by this command:
+//
+//	mockgen -destination=mock1/interfaces_mock.go -build_flags=-tags=tag1 . Interface
+//
+
+// Package mock_build_flags is a generated GoMock package.
+package mock_build_flags
+
+import (
+	reflect "reflect"
+
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockInterface is a mock of Interface interface.
+type MockInterface struct {
+	ctrl     *gomock.Controller
+	recorder *MockInterfaceMockRecorder
+	isgomock struct{}
+}
+
+// MockInterfaceMockRecorder is the mock recorder for MockInterface.
+type MockInterfaceMockRecorder struct {
+	mock *MockInterface
+}
+
+// NewMockInterface creates a new mock instance.
+func NewMockInterface(ctrl *gomock.Controller) *MockInterface {
+	mock := &MockInterface{ctrl: ctrl}
+	mock.recorder = &MockInterfaceMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockInterface) EXPECT() *MockInterfaceMockRecorder {
+	return m.recorder
+}
+
+// HelloWorld mocks base method.
+func (m *MockInterface) HelloWorld() string {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "HelloWorld")
+	ret0, _ := ret[0].(string)
+	return ret0
+}
+
+// HelloWorld indicates an expected call of HelloWorld.
+func (mr *MockInterfaceMockRecorder) HelloWorld() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HelloWorld", reflect.TypeOf((*MockInterface)(nil).HelloWorld))
+}
diff --git a/mockgen/internal/tests/build_flags/mock2/interfaces_mock.go b/mockgen/internal/tests/build_flags/mock2/interfaces_mock.go
new file mode 100644
index 0000000..4f21187
--- /dev/null
+++ b/mockgen/internal/tests/build_flags/mock2/interfaces_mock.go
@@ -0,0 +1,52 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: go.uber.org/mock/mockgen/internal/tests/build_flags (interfaces: Interface)
+//
+// Generated by this command:
+//
+//	mockgen -destination=mock2/interfaces_mock.go -build_flags=-race -tags=tag2 . Interface
+//
+
+// Package mock_build_flags is a generated GoMock package.
+package mock_build_flags
+
+import (
+	reflect "reflect"
+
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockInterface is a mock of Interface interface.
+type MockInterface struct {
+	ctrl     *gomock.Controller
+	recorder *MockInterfaceMockRecorder
+	isgomock struct{}
+}
+
+// MockInterfaceMockRecorder is the mock recorder for MockInterface.
+type MockInterfaceMockRecorder struct {
+	mock *MockInterface
+}
+
+// NewMockInterface creates a new mock instance.
+func NewMockInterface(ctrl *gomock.Controller) *MockInterface {
+	mock := &MockInterface{ctrl: ctrl}
+	mock.recorder = &MockInterfaceMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockInterface) EXPECT() *MockInterfaceMockRecorder {
+	return m.recorder
+}
+
+// Foo mocks base method.
+func (m *MockInterface) Foo() {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "Foo")
+}
+
+// Foo indicates an expected call of Foo.
+func (mr *MockInterfaceMockRecorder) Foo() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Foo", reflect.TypeOf((*MockInterface)(nil).Foo))
+}
diff --git a/mockgen/package_mode.go b/mockgen/package_mode.go
index 540a83e..abc9c7a 100644
--- a/mockgen/package_mode.go
+++ b/mockgen/package_mode.go
@@ -2,13 +2,19 @@ package main
 
 import (
 	"errors"
+	"flag"
 	"fmt"
 	"go/types"
+	"strings"
 
 	"go.uber.org/mock/mockgen/model"
 	"golang.org/x/tools/go/packages"
 )
 
+var (
+	buildFlags = flag.String("build_flags", "", "(package mode) Additional flags for go build.")
+)
+
 type packageModeParser struct {
 	pkgName string
 }
@@ -34,8 +40,14 @@ func (p *packageModeParser) parsePackage(packageName string, ifaces []string) (*
 }
 
 func (p *packageModeParser) loadPackage(packageName string) (*packages.Package, error) {
+	var buildFlagsSet []string
+	if *buildFlags != "" {
+		buildFlagsSet = strings.Split(*buildFlags, " ")
+	}
+
 	cfg := &packages.Config{
-		Mode: packages.NeedDeps | packages.NeedImports | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedEmbedFiles,
+		Mode:       packages.NeedDeps | packages.NeedImports | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedEmbedFiles,
+		BuildFlags: buildFlagsSet,
 	}
 	pkgs, err := packages.Load(cfg, packageName)
 	if err != nil {