diff --git a/common/command/build_flags.go b/common/command/build_flags.go
index 167e13310..d08ca58b8 100644
--- a/common/command/build_flags.go
+++ b/common/command/build_flags.go
@@ -12,6 +12,7 @@ func BuildOptionFlags(fs *flag.FlagSet, f *BuildOptions) {
 	fs.Var((*SliceValue)(&f.Except), "except", "build all builds except these")
 	fs.Var((*SliceValue)(&f.Only), "only", "only build the given builds by name")
 	fs.Var((*userVarValue)(&f.UserVars), "var", "specify a user variable")
+	fs.Var((*AppendSliceValue)(&f.UserVarFiles), "var-file", "file with user variables")
 }
 
 // userVarValue is a flag.Value that parses out user variables in
diff --git a/common/command/build_flags_test.go b/common/command/build_flags_test.go
index b4f9753fe..5d39eb946 100644
--- a/common/command/build_flags_test.go
+++ b/common/command/build_flags_test.go
@@ -17,6 +17,8 @@ func TestBuildOptionFlags(t *testing.T) {
 		"-var=foo=bar",
 		"-var", "bar=baz",
 		"-var=foo=bang",
+		"-var-file=foo",
+		"-var-file=bar",
 	}
 
 	err := fs.Parse(args)
@@ -45,6 +47,11 @@ func TestBuildOptionFlags(t *testing.T) {
 	if opts.UserVars["bar"] != "baz" {
 		t.Fatalf("bad: %#v", opts.UserVars)
 	}
+
+	expected = []string{"foo", "bar"}
+	if !reflect.DeepEqual(opts.UserVarFiles, expected) {
+		t.Fatalf("bad: %#v", opts.UserVarFiles)
+	}
 }
 
 func TestUserVarValue_implements(t *testing.T) {
diff --git a/common/command/flag_slice_value.go b/common/command/flag_slice_value.go
index b6f466463..8989dedad 100644
--- a/common/command/flag_slice_value.go
+++ b/common/command/flag_slice_value.go
@@ -2,6 +2,23 @@ package command
 
 import "strings"
 
+// AppendSliceValue implements the flag.Value interface and allows multiple
+// calls to the same variable to append a list.
+type AppendSliceValue []string
+
+func (s *AppendSliceValue) String() string {
+	return strings.Join(*s, ",")
+}
+
+func (s *AppendSliceValue) Set(value string) error {
+	if *s == nil {
+		*s = make([]string, 0, 1)
+	}
+
+	*s = append(*s, value)
+	return nil
+}
+
 // SliceValue implements the flag.Value interface and allows a list of
 // strings to be given on the command line and properly parsed into a slice
 // of strings internally.
diff --git a/common/command/flag_slice_value_test.go b/common/command/flag_slice_value_test.go
index 1b9e2a762..ca80c9d9f 100644
--- a/common/command/flag_slice_value_test.go
+++ b/common/command/flag_slice_value_test.go
@@ -6,6 +6,32 @@ import (
 	"testing"
 )
 
+func TestAppendSliceValue_implements(t *testing.T) {
+	var raw interface{}
+	raw = new(AppendSliceValue)
+	if _, ok := raw.(flag.Value); !ok {
+		t.Fatalf("AppendSliceValue should be a Value")
+	}
+}
+
+func TestAppendSliceValueSet(t *testing.T) {
+	sv := new(AppendSliceValue)
+	err := sv.Set("foo")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	err = sv.Set("bar")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	expected := []string{"foo", "bar"}
+	if !reflect.DeepEqual([]string(*sv), expected) {
+		t.Fatalf("Bad: %#v", sv)
+	}
+}
+
 func TestSliceValue_implements(t *testing.T) {
 	var raw interface{}
 	raw = new(SliceValue)
diff --git a/common/command/template.go b/common/command/template.go
index 3f7a8b9c1..4c14dd038 100644
--- a/common/command/template.go
+++ b/common/command/template.go
@@ -1,18 +1,22 @@
 package command
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"github.com/mitchellh/packer/packer"
+	"io/ioutil"
 	"log"
+	"os"
 )
 
 // BuildOptions is a set of options related to builds that can be set
 // from the command line.
 type BuildOptions struct {
-	UserVars map[string]string
-	Except   []string
-	Only     []string
+	UserVarFiles []string
+	UserVars     map[string]string
+	Except       []string
+	Only         []string
 }
 
 // Validate validates the options
@@ -21,6 +25,14 @@ func (f *BuildOptions) Validate() error {
 		return errors.New("Only one of '-except' or '-only' may be specified.")
 	}
 
+	if len(f.UserVarFiles) > 0 {
+		for _, path := range f.UserVarFiles {
+			if _, err := os.Stat(path); err != nil {
+				return fmt.Errorf("Cannot access: %s", path)
+			}
+		}
+	}
+
 	return nil
 }
 
@@ -29,6 +41,18 @@ func (f *BuildOptions) Validate() error {
 func (f *BuildOptions) AllUserVars() (map[string]string, error) {
 	all := make(map[string]string)
 
+	// Copy in the variables from the files
+	for _, path := range f.UserVarFiles {
+		fileVars, err := readFileVars(path)
+		if err != nil {
+			return nil, err
+		}
+
+		for k, v := range fileVars {
+			all[k] = v
+		}
+	}
+
 	// Copy in the command-line vars
 	for k, v := range f.UserVars {
 		all[k] = v
@@ -84,3 +108,18 @@ func (f *BuildOptions) Builds(t *packer.Template, cf *packer.ComponentFinder) ([
 
 	return builds, nil
 }
+
+func readFileVars(path string) (map[string]string, error) {
+	bytes, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	vars := make(map[string]string)
+	err = json.Unmarshal(bytes, &vars)
+	if err != nil {
+		return nil, err
+	}
+
+	return vars, nil
+}
diff --git a/common/command/template_test.go b/common/command/template_test.go
index 18a9805db..ae1bd6ea3 100644
--- a/common/command/template_test.go
+++ b/common/command/template_test.go
@@ -35,3 +35,19 @@ func TestBuildOptionsValidate(t *testing.T) {
 		t.Fatalf("err: %s", err)
 	}
 }
+
+func TestBuildOptionsValidate_userVarFiles(t *testing.T) {
+	bf := new(BuildOptions)
+
+	err := bf.Validate()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Non-existent file
+	bf.UserVarFiles = []string{"ireallyshouldntexistanywhere"}
+	err = bf.Validate()
+	if err == nil {
+		t.Fatal("should error")
+	}
+}