diff --git a/plugins/guests/linux/cap/mount_smb_shared_folder.rb b/plugins/guests/linux/cap/mount_smb_shared_folder.rb
index dfc592639..86c1c66f6 100644
--- a/plugins/guests/linux/cap/mount_smb_shared_folder.rb
+++ b/plugins/guests/linux/cap/mount_smb_shared_folder.rb
@@ -25,16 +25,19 @@ module VagrantPlugins
           # Ensure password is scrubbed
           Vagrant::Util::CredentialScrubber.sensitive(smb_password)
 
-          options[:mount_options] ||= []
+          mnt_opts = []
           if machine.env.host.capability?(:smb_mount_options)
-            options[:mount_options] += machine.env.host.capability(:smb_mount_options)
+            mnt_opts += machine.env.host.capability(:smb_mount_options)
           else
-            options[:mount_options] << "sec=ntlm"
+            mnt_opts << "sec=ntlmssp"
           end
-          options[:mount_options] << "credentials=/etc/smb_creds_#{name}"
+          mnt_opts << "credentials=/etc/smb_creds_#{name}"
+          mnt_opts << "uid=#{mount_uid}"
+          mnt_opts << "gid=#{mount_gid}"
 
-          mount_options = "-o uid=#{mount_uid},gid=#{mount_gid}"
-          mount_options += ",#{Array(options[:mount_options]).join(",")}" if options[:mount_options]
+          mnt_opts = merge_mount_options(mnt_opts, options[:mount_options] || [])
+
+          mount_options = "-o #{mnt_opts.join(",")}"
           mount_command = "mount -t cifs #{mount_options} #{mount_device} #{expanded_guest_path}"
 
           # Create the guest path if it doesn't exist
@@ -76,6 +79,21 @@ SCRIPT
 
           emit_upstart_notification(machine, expanded_guest_path)
         end
+
+        def self.merge_mount_options(base, overrides)
+          base = base.join(",").split(",")
+          overrides = overrides.join(",").split(",")
+          b_kv = Hash[base.map{|item| item.split("=", 2) }]
+          o_kv = Hash[overrides.map{|item| item.split("=", 2) }]
+          merged = {}.tap do |opts|
+            (b_kv.keys + o_kv.keys).uniq.each do |key|
+              opts[key] = o_kv.fetch(key, b_kv[key])
+            end
+          end
+          merged.map do |key, value|
+            [key, value].compact.join("=")
+          end
+        end
       end
     end
   end
diff --git a/test/unit/plugins/guests/linux/cap/mount_smb_shared_folder.rb b/test/unit/plugins/guests/linux/cap/mount_smb_shared_folder.rb
index 62d4745f2..dd5e7c484 100644
--- a/test/unit/plugins/guests/linux/cap/mount_smb_shared_folder.rb
+++ b/test/unit/plugins/guests/linux/cap/mount_smb_shared_folder.rb
@@ -7,7 +7,9 @@ describe "VagrantPlugins::GuestLinux::Cap::MountSMBSharedFolder" do
       .guest_capabilities[:linux]
   end
 
-  let(:machine) { double("machine") }
+  let(:machine) { double("machine", env: env) }
+  let(:env) { double("env", host: host) }
+  let(:host) { double("host") }
   let(:guest) { double("guest") }
   let(:comm) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
   let(:mount_owner){ "vagrant" }
@@ -29,6 +31,7 @@ describe "VagrantPlugins::GuestLinux::Cap::MountSMBSharedFolder" do
 
   before do
     allow(machine).to receive(:communicate).and_return(comm)
+    allow(host).to receive(:capability?).and_return(false)
   end
 
   after do
@@ -72,5 +75,57 @@ describe "VagrantPlugins::GuestLinux::Cap::MountSMBSharedFolder" do
       expect(comm).to receive(:sudo).with(/emit/)
       cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
     end
+
+    context "with custom mount options" do
+      let(:folder_options) do
+        {
+          owner: mount_owner,
+          group: mount_group,
+          smb_host: "localhost",
+          smb_username: "user",
+          smb_password: "pass",
+          mount_options: ["ro", "sec=custom"]
+        }
+      end
+
+      it "adds given mount options to command" do
+        expect(comm).to receive(:sudo).with(/ro/, any_args)
+        cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
+      end
+
+      it "replaces defined options" do
+        expect(comm).to receive(:sudo).with(/sec=custom/, any_args)
+        cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
+      end
+
+      it "does not include replaced options" do
+        expect(comm).not_to receive(:sudo).with(/sec=ntlm/, any_args)
+        cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
+      end
+    end
+  end
+
+  describe ".merge_mount_options" do
+    let(:base){ ["opt1", "opt2=on", "opt3", "opt4,opt5=off"] }
+    let(:override){ ["opt8", "opt4=on,opt6,opt7=true"] }
+
+    context "with no override" do
+      it "should split options into individual options" do
+        result = cap.merge_mount_options(base, [])
+        expect(result.size).to eq(5)
+      end
+    end
+
+    context "with overrides" do
+      it "should merge all options" do
+        result = cap.merge_mount_options(base, override)
+        expect(result.size).to eq(8)
+      end
+
+      it "should override options defined in base" do
+        result = cap.merge_mount_options(base, override)
+        expect(result).to include("opt4=on")
+      end
+    end
   end
 end