diff --git a/lib/vagrant/util/platform.rb b/lib/vagrant/util/platform.rb
index 944ca42ea..1ec14819c 100644
--- a/lib/vagrant/util/platform.rb
+++ b/lib/vagrant/util/platform.rb
@@ -213,13 +213,20 @@ module Vagrant
           return path if !cygwin?
 
           # Replace all "\" with "/", otherwise cygpath doesn't work.
-          path = path.gsub("\\", "/")
+          path = unix_windows_path(path)
 
           # Call out to cygpath and gather the result
           process = Subprocess.execute("cygpath", "-w", "-l", "-a", path.to_s)
           return process.stdout.chomp
         end
 
+        # This takes any path and converts Windows-style path separators
+        # to Unix-like path separators.
+        # @return [String]
+        def unix_windows_path(path)
+          path.gsub("\\", "/")
+        end
+
         # This checks if the filesystem is case sensitive. This is not a
         # 100% correct check, since it is possible that the temporary
         # directory runs a different filesystem than the root directory.
diff --git a/plugins/communicators/ssh/communicator.rb b/plugins/communicators/ssh/communicator.rb
index 47cd01c89..9389e83b2 100644
--- a/plugins/communicators/ssh/communicator.rb
+++ b/plugins/communicators/ssh/communicator.rb
@@ -65,7 +65,7 @@ module VagrantPlugins
           while true
             ssh_info = @machine.ssh_info
             break if ssh_info
-            sleep 0.5
+            sleep(0.5)
           end
 
           # Got it! Let the user know what we're connecting to.
@@ -354,6 +354,11 @@ module VagrantPlugins
         wait_for_ready(5)
       end
 
+      def generate_environment_export(env_key, env_value)
+        template = machine_config_ssh.export_command_template
+        template.sub("%ENV_KEY%", env_key).sub("%ENV_VALUE%", env_value) + "\n"
+      end
+
       protected
 
       # Opens an SSH connection and yields it to a block.
@@ -628,7 +633,7 @@ module VagrantPlugins
             end
 
             # Set the terminal
-            ch2.send_data generate_environment_export("TERM", "vt100")
+            ch2.send_data(generate_environment_export("TERM", "vt100"))
 
             # Set SSH_AUTH_SOCK if we are in sudo and forwarding agent.
             # This is to work around often misconfigured boxes where
@@ -651,7 +656,7 @@ module VagrantPlugins
                 @logger.warn("No SSH_AUTH_SOCK found despite forward_agent being set.")
               else
                 @logger.info("Setting SSH_AUTH_SOCK remotely: #{auth_socket}")
-                ch2.send_data generate_environment_export("SSH_AUTH_SOCK", auth_socket)
+                ch2.send_data(generate_environment_export("SSH_AUTH_SOCK", auth_socket))
               end
             end
 
@@ -669,11 +674,11 @@ module VagrantPlugins
               data += "printf #{PTY_DELIM_END}\n"
               data += "exit $exitcode\n"
               data = data.force_encoding('ASCII-8BIT')
-              ch2.send_data data
+              ch2.send_data(data)
             else
-              ch2.send_data "printf '#{CMD_GARBAGE_MARKER}'\n(>&2 printf '#{CMD_GARBAGE_MARKER}')\n#{command}\n".force_encoding('ASCII-8BIT')
+              ch2.send_data("printf '#{CMD_GARBAGE_MARKER}'\n(>&2 printf '#{CMD_GARBAGE_MARKER}')\n#{command}\n".force_encoding('ASCII-8BIT'))
               # Remember to exit or this channel will hang open
-              ch2.send_data "exit\n"
+              ch2.send_data("exit\n")
             end
 
             # Send eof to let server know we're done
@@ -759,11 +764,6 @@ module VagrantPlugins
         return File.read(path).chomp == source_path.read.chomp
       end
 
-      def generate_environment_export(env_key, env_value)
-        template = machine_config_ssh.export_command_template
-        template.sub("%ENV_KEY%", env_key).sub("%ENV_VALUE%", env_value) + "\n"
-      end
-
       def create_remote_directory(dir)
         execute("mkdir -p \"#{dir}\"")
       end
diff --git a/plugins/communicators/winssh/communicator.rb b/plugins/communicators/winssh/communicator.rb
index e7de70675..00726c2d3 100644
--- a/plugins/communicators/winssh/communicator.rb
+++ b/plugins/communicators/winssh/communicator.rb
@@ -54,7 +54,7 @@ SCRIPT
           end
 
           tfile.close
-          upload(tfile.path, remote_name)
+          upload(tfile.path, remote_name, mkdir: false)
           tfile.delete
 
           base_cmd = shell_cmd(opts.merge(shell: base_cmd))
@@ -156,6 +156,74 @@ SCRIPT
         @machine.config.winssh
       end
 
+      def upload(from, to, **opts)
+        opts = {
+          mkdir: true
+        }.merge(opts)
+
+        mkdir = opts[:mkdir]
+
+        to = Vagrant::Util::Platform.unix_windows_path(to)
+        @logger.debug("Uploading: #{from} to #{to}")
+
+        if File.directory?(from)
+          if from.end_with?(".")
+            @logger.debug("Uploading directory contents of: #{from}")
+            from = from.sub(/\.$/, "")
+          else
+            @logger.debug("Uploading full directory container of: #{from}")
+            to = File.join(to, File.basename(File.expand_path(from)))
+          end
+        end
+
+        scp_connect do |scp|
+          uploader = lambda do |path, remote_dest=nil|
+            if File.directory?(path)
+              Dir.new(path).each do |entry|
+                next if entry == "." || entry == ".."
+                full_path = File.join(path, entry)
+                dest = File.join(to, path.sub(/^#{Regexp.escape(from)}/, ""))
+                create_remote_directory(dest) if mkdir
+                uploader.call(full_path, dest)
+              end
+            else
+              if remote_dest
+                dest = File.join(remote_dest, File.basename(path))
+              else
+                dest = to
+                if to.end_with?(File::SEPARATOR)
+                  dest = File.join(to, File.basename(path))
+                end
+              end
+              @logger.debug("Ensuring remote directory exists for destination upload")
+              create_remote_directory(File.dirname(dest)) if mkdir
+              @logger.debug("Uploading file #{path} to remote #{dest}")
+              upload_file = File.open(path, "rb")
+              begin
+                scp.upload!(upload_file, dest)
+              ensure
+                upload_file.close
+              end
+            end
+          end
+          uploader.call(from)
+        end
+      rescue RuntimeError => e
+        # Net::SCP raises a runtime error for this so the only way we have
+        # to really catch this exception is to check the message to see if
+        # it is something we care about. If it isn't, we re-raise.
+        raise if e.message !~ /Permission denied/
+
+        # Otherwise, it is a permission denied, so let's raise a proper
+        # exception
+        raise Vagrant::Errors::SCPPermissionDenied,
+          from: from.to_s,
+          to: to.to_s
+      end
+
+      def create_remote_directory(dir)
+        execute("dir \"#{dir}\"\n if errorlevel 1 (mkdir \"#{dir}\")", shell: "cmd")
+      end
     end
   end
 end
diff --git a/plugins/guests/windows/cap/public_key.rb b/plugins/guests/windows/cap/public_key.rb
index 4359625af..1dbb67151 100644
--- a/plugins/guests/windows/cap/public_key.rb
+++ b/plugins/guests/windows/cap/public_key.rb
@@ -37,7 +37,7 @@ module VagrantPlugins
 
           # Ensure the user's ssh directory exists
           remote_ssh_dir = "#{home_dir}\\.ssh"
-          comm.execute("dir \"#{remote_ssh_dir}\"\n if errorlevel 1 (mkdir \"#{remote_ssh_dir}\")", shell: "cmd")
+          comm.create_remote_directory(remote_ssh_dir)
           remote_upload_path = "#{temp_dir}\\vagrant-insert-pubkey-#{Time.now.to_i}"
           remote_authkeys_path = "#{remote_ssh_dir}\\authorized_keys"
 
@@ -55,7 +55,7 @@ module VagrantPlugins
           File.write(keys_file.path, keys.join("\r\n") + "\r\n")
           comm.upload(keys_file.path, remote_upload_path)
           keys_file.delete
-          comm.execute <<-EOC.gsub(/^\s*/, ""), shell: "powershell"
+          comm.execute(<<-EOC.gsub(/^\s*/, ""), shell: "powershell")
             Set-Acl "#{remote_upload_path}" (Get-Acl "#{remote_authkeys_path}")
             Move-Item -Force "#{remote_upload_path}" "#{remote_authkeys_path}"
           EOC
diff --git a/plugins/provisioners/shell/config.rb b/plugins/provisioners/shell/config.rb
index 74a74cf13..9f035c1c9 100644
--- a/plugins/provisioners/shell/config.rb
+++ b/plugins/provisioners/shell/config.rb
@@ -55,7 +55,7 @@ module VagrantPlugins
         @sha384               = nil if @sha384 == UNSET_VALUE
         @sha512               = nil if @sha512 == UNSET_VALUE
         @env                  = {}  if @env == UNSET_VALUE
-        @upload_path          = "/tmp/vagrant-shell" if @upload_path == UNSET_VALUE
+        @upload_path          = nil if @upload_path == UNSET_VALUE
         @privileged           = true if @privileged == UNSET_VALUE
         @binary               = false if @binary == UNSET_VALUE
         @keep_color           = false if @keep_color == UNSET_VALUE
@@ -109,11 +109,6 @@ module VagrantPlugins
           errors << I18n.t("vagrant.provisioners.shell.env_must_be_a_hash")
         end
 
-        # There needs to be a path to upload the script to
-        if !upload_path
-          errors << I18n.t("vagrant.provisioners.shell.upload_path_not_set")
-        end
-
         if !args_valid?
           errors << I18n.t("vagrant.provisioners.shell.args_bad_type")
         end
diff --git a/plugins/provisioners/shell/provisioner.rb b/plugins/provisioners/shell/provisioner.rb
index 8175d82b7..1758a995d 100644
--- a/plugins/provisioners/shell/provisioner.rb
+++ b/plugins/provisioners/shell/provisioner.rb
@@ -38,6 +38,22 @@ module VagrantPlugins
         end
       end
 
+      def upload_path
+        if !defined?(@_upload_path)
+          @_upload_path = config.upload_path.to_s
+
+          if @_upload_path.empty?
+            case @machine.config.vm.communicator
+            when :winssh
+              @_upload_path = "C:\\Windows\\Temp\\vagrant-shell"
+            else
+              @_upload_path = "/tmp/vagrant-shell"
+            end
+          end
+        end
+        @_upload_path
+      end
+
       protected
 
       # This handles outputting the communication data back to the UI
@@ -63,10 +79,10 @@ module VagrantPlugins
         env = config.env.map { |k,v| "#{k}=#{quote_and_escape(v.to_s)}" }
         env = env.join(" ")
 
-        command =  "chmod +x '#{config.upload_path}'"
+        command =  "chmod +x '#{upload_path}'"
         command << " &&"
         command << " #{env}" if !env.empty?
-        command << " #{config.upload_path}#{args}"
+        command << " #{upload_path}#{args}"
 
         with_script_file do |path|
           # Upload the script to the machine
@@ -79,10 +95,10 @@ module VagrantPlugins
             end
 
             user = info[:username]
-            comm.sudo("chown -R #{user} #{config.upload_path}",
+            comm.sudo("chown -R #{user} #{upload_path}",
                       error_check: false)
 
-            comm.upload(path.to_s, config.upload_path)
+            comm.upload(path.to_s, upload_path)
 
             if config.name
               @machine.ui.detail(I18n.t("vagrant.provisioners.shell.running",
@@ -114,7 +130,6 @@ module VagrantPlugins
           # Upload the script to the machine
           @machine.communicate.tap do |comm|
             env = config.env.map{|k,v| comm.generate_environment_export(k, v)}.join
-            upload_path = config.upload_path.to_s
             if File.extname(upload_path).empty?
               remote_ext = @machine.config.winssh.shell == "powershell" ? "ps1" : "bat"
               upload_path << ".#{remote_ext}"
@@ -174,7 +189,6 @@ module VagrantPlugins
           @machine.communicate.tap do |comm|
             # Make sure that the upload path has an extension, since
             # having an extension is critical for Windows execution
-            upload_path = config.upload_path.to_s
             if File.extname(upload_path) == ""
               upload_path += File.extname(path.to_s)
             end
diff --git a/test/unit/plugins/communicators/winssh/communicator_test.rb b/test/unit/plugins/communicators/winssh/communicator_test.rb
index 8da9b2196..931d51db3 100644
--- a/test/unit/plugins/communicators/winssh/communicator_test.rb
+++ b/test/unit/plugins/communicators/winssh/communicator_test.rb
@@ -69,10 +69,10 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
   # by providing to `before`
   connection_setup = proc do
     allow(connection).to receive(:logger)
-    allow(connection).to receive(:closed?).and_return false
+    allow(connection).to receive(:closed?).and_return(false)
     allow(connection).to receive(:open_channel).
       and_yield(channel).and_return(channel)
-    allow(channel).to receive(:wait).and_return true
+    allow(channel).to receive(:wait).and_return(true)
     allow(channel).to receive(:close)
     allow(command_channel).to receive(:send_data)
     allow(command_channel).to receive(:eof!)
@@ -88,7 +88,7 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     allow(channel).to receive(:on_request)
     allow(channel).to receive(:on_process)
     allow(channel).to receive(:exec).with(anything).
-      and_yield(command_channel, '').and_return channel
+      and_yield(command_channel, '').and_return(channel)
     expect(command_channel).to receive(:on_request).with('exit-status').
       and_yield(nil, exit_data)
     # Return mocked net-ssh connection during setup
@@ -132,11 +132,11 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
 
     context "with an invalid shell test" do
       before do
-        expect(exit_data).to receive(:read_long).and_return 1
+        expect(exit_data).to receive(:read_long).and_return(1)
       end
 
       it "returns raises SSHInvalidShell error" do
-        expect{ communicator.ready? }.to raise_error Vagrant::Errors::SSHInvalidShell
+        expect{ communicator.ready? }.to raise_error(Vagrant::Errors::SSHInvalidShell)
       end
     end
   end
@@ -215,7 +215,7 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
 
     context "with exit code as non-zero" do
       before do
-        expect(exit_data).to receive(:read_long).and_return 1
+        expect(exit_data).to receive(:read_long).and_return(1)
       end
 
       it "returns false" do
@@ -224,7 +224,7 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     end
   end
 
-  describe ".upload" do
+  describe "#upload" do
     before do
       allow(communicator).to receive(:create_remote_directory)
       expect(communicator).to receive(:scp_connect).and_yield(scp)
@@ -241,7 +241,9 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     it "uploads a file if local path is a file" do
       file = Tempfile.new('vagrant-test')
       begin
-        expect(scp).to receive(:upload!).with(instance_of(File), 'C:\destination\file')
+        expect(scp).to receive(:upload!).with(instance_of(File), 'C:/destination/file')
+        expect(Vagrant::Util::Platform).to receive(:unix_windows_path).with('C:\destination\file').
+          and_call_original
         communicator.upload(file.path, 'C:\destination\file')
       ensure
         file.delete
@@ -251,7 +253,7 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     it "raises custom error on permission errors" do
       file = Tempfile.new('vagrant-test')
       begin
-        expect(scp).to receive(:upload!).with(instance_of(File), 'C:\destination\file').
+        expect(scp).to receive(:upload!).with(instance_of(File), 'C:/destination/file').
           and_raise("Permission denied")
         expect{ communicator.upload(file.path, 'C:\destination\file') }.to(
           raise_error(Vagrant::Errors::SCPPermissionDenied)
@@ -264,7 +266,7 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     it "does not raise custom error on non-permission errors" do
       file = Tempfile.new('vagrant-test')
       begin
-        expect(scp).to receive(:upload!).with(instance_of(File), 'C:\destination\file').
+        expect(scp).to receive(:upload!).with(instance_of(File), 'C:/destination/file').
           and_raise("Some other error")
         expect{ communicator.upload(file.path, 'C:\destination\file') }.to raise_error(RuntimeError)
       ensure
@@ -525,4 +527,12 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
       end
     end
   end
+
+  describe "#shell_execute" do
+    before(&connection_setup)
+    it "should not create a directory for the command wrapper script" do
+      expect(communicator).to receive(:upload).with(anything, anything, hash_including(mkdir: false))
+      communicator.shell_execute(connection, "dir")
+    end
+  end
 end
diff --git a/test/unit/plugins/provisioners/shell/config_test.rb b/test/unit/plugins/provisioners/shell/config_test.rb
index 3a843ca20..cda5de47a 100644
--- a/test/unit/plugins/provisioners/shell/config_test.rb
+++ b/test/unit/plugins/provisioners/shell/config_test.rb
@@ -7,6 +7,7 @@ describe "VagrantPlugins::Shell::Config" do
 
   let(:machine)          { double('machine', env: Vagrant::Environment.new) }
   let(:file_that_exists) { File.expand_path(__FILE__)                       }
+  let(:unset_value)      { Vagrant::Plugin::V2::Config::UNSET_VALUE         }
 
   subject { described_class.new }
 
@@ -142,6 +143,15 @@ describe "VagrantPlugins::Shell::Config" do
       result = subject.validate(machine)
       expect(result["shell provisioner"]).to be_empty
     end
+
+    it "returns no error if upload_path is unset" do
+      subject.inline = "script"
+      subject.upload_path = unset_value
+      subject.finalize!
+
+      result = subject.validate(machine)
+      expect(result["shell provisioner"]).to be_empty
+    end
   end
 
   describe 'finalize!' do
@@ -150,7 +160,7 @@ describe "VagrantPlugins::Shell::Config" do
       subject.args = 1
       subject.finalize!
 
-      expect(subject.args).to eq '1'
+      expect(subject.args).to eq('1')
     end
 
     it 'changes integer args in arrays into strings' do
@@ -158,7 +168,14 @@ describe "VagrantPlugins::Shell::Config" do
       subject.args = ["string", 1, 2]
       subject.finalize!
 
-      expect(subject.args).to eq ["string", '1', '2']
+      expect(subject.args).to eq(["string", '1', '2'])
+    end
+
+    it "no longer sets a default for upload_path" do
+      subject.upload_path = unset_value
+      subject.finalize!
+
+      expect(subject.upload_path).to eq(nil)
     end
 
     context "with sensitive option enabled" do
diff --git a/test/unit/plugins/provisioners/shell/provisioner_test.rb b/test/unit/plugins/provisioners/shell/provisioner_test.rb
index b117d76be..45625a60e 100644
--- a/test/unit/plugins/provisioners/shell/provisioner_test.rb
+++ b/test/unit/plugins/provisioners/shell/provisioner_test.rb
@@ -323,4 +323,82 @@ describe "Vagrant::Shell::Provisioner" do
       end
     end
   end
+
+  describe "#upload_path" do
+    context "when upload path is not set" do
+      let(:vsp) {
+        VagrantPlugins::Shell::Provisioner.new(machine, config)
+      }
+
+      let(:config) {
+        double(
+          :config,
+          :args        => "doesn't matter",
+          :env         => {},
+          :upload_path => nil,
+          :remote?     => false,
+          :path        => "doesn't matter",
+          :inline      => "doesn't matter",
+          :binary      => false,
+          :reset       => true,
+          :reboot      => false,
+        )
+      }
+
+      it "should default to /tmp/vagrant-shell" do
+        expect(vsp.upload_path).to eq("/tmp/vagrant-shell")
+      end
+
+      context "with winssh provisioner" do
+        before do
+          allow(machine).to receive_message_chain(:config, :vm, :communicator).and_return(:winssh)
+        end
+
+        it "should default to C:\\Windows\\Temp\\vagrant-shell" do
+          expect(vsp.upload_path).to eq("C:\\Windows\\Temp\\vagrant-shell")
+        end
+      end
+    end
+
+    context "when upload_path is set" do
+      let(:config) {
+        double(
+          :config,
+          :args        => "doesn't matter",
+          :env         => {},
+          :upload_path => "arbitrary",
+          :remote?     => false,
+          :path        => "doesn't matter",
+          :inline      => "doesn't matter",
+          :binary      => false,
+          :reset       => true,
+          :reboot      => false,
+        )
+      }
+
+      let(:vsp) {
+        VagrantPlugins::Shell::Provisioner.new(machine, config)
+      }
+
+      it "should use the value from from config" do
+        expect(vsp.upload_path).to eq("arbitrary")
+      end
+    end
+
+    context "with cached value" do
+      let(:config) { double(:config) }
+
+      let(:vsp) {
+        VagrantPlugins::Shell::Provisioner.new(machine, config)
+      }
+
+      before do
+        vsp.instance_variable_set(:@_upload_path, "anything")
+      end
+
+      it "should use cached value" do
+        expect(vsp.upload_path).to eq("anything")
+      end
+    end
+  end
 end
diff --git a/test/unit/vagrant/util/platform_test.rb b/test/unit/vagrant/util/platform_test.rb
index 7149a66e3..6b71329e9 100644
--- a/test/unit/vagrant/util/platform_test.rb
+++ b/test/unit/vagrant/util/platform_test.rb
@@ -280,7 +280,7 @@ describe Vagrant::Util::Platform do
       end
 
       it "should return false when path is within /mnt" do
-        expect(subject.wsl_path?("/mnt/c")).to be false
+        expect(subject.wsl_path?("/mnt/c")).to be(false)
       end
     end
 
@@ -533,5 +533,11 @@ EOF
         expect(subject.wsl_drvfs_path?("/home/vagrant/some/path")).to be_falsey
       end
     end
+
+    describe ".unix_windows_path" do
+      it "takes a windows path and returns a unixy path" do
+        expect(subject.unix_windows_path("C:\\Temp\\Windows")).to eq("C:/Temp/Windows")
+      end
+    end
   end
 end
diff --git a/website/source/docs/vagrantfile/winssh_settings.html.md b/website/source/docs/vagrantfile/winssh_settings.html.md
index 98b0ca103..b77acf063 100644
--- a/website/source/docs/vagrantfile/winssh_settings.html.md
+++ b/website/source/docs/vagrantfile/winssh_settings.html.md
@@ -74,3 +74,5 @@ being executed.
 
 * `config.winssh.upload_directory` (string) - The upload directory used on the guest
 to store scripts for execute. This is set to `C:\Windows\Temp` by default.
+Vagrant will not attempt to create this directory, so it must already exist on
+the guest.