diff --git a/cmd/server.go b/cmd/server.go
index 3bfb2a9115..e6283d42d0 100644
--- a/cmd/server.go
+++ b/cmd/server.go
@@ -72,6 +72,7 @@ const (
 	SlackTokenFlag             = "slack-token"
 	SSLCertFileFlag            = "ssl-cert-file"
 	SSLKeyFileFlag             = "ssl-key-file"
+	TFDownloadURLFlag          = "tf-download-url"
 	TFEHostnameFlag            = "tfe-hostname"
 	TFETokenFlag               = "tfe-token"
 	WriteGitCredsFlag          = "write-git-creds"
@@ -86,6 +87,7 @@ const (
 	DefaultGitlabHostname   = "gitlab.com"
 	DefaultLogLevel         = "info"
 	DefaultPort             = 4141
+	DefaultTFDownloadURL    = "https://releases.hashicorp.com"
 	DefaultTFEHostname      = "app.terraform.io"
 )
 
@@ -202,6 +204,10 @@ var stringFlags = map[string]stringFlag{
 	SSLKeyFileFlag: {
 		description: fmt.Sprintf("File containing x509 private key matching --%s.", SSLCertFileFlag),
 	},
+	TFDownloadURLFlag: {
+		description:  "The URL to download Terraform from.",
+		defaultValue: DefaultTFDownloadURL,
+	},
 	TFEHostnameFlag: {
 		description:  "Hostname of your Terraform Enterprise installation. If using Terraform Cloud no need to set.",
 		defaultValue: DefaultTFEHostname,
@@ -454,6 +460,9 @@ func (s *ServerCmd) setDefaults(c *server.UserConfig) {
 	if c.Port == 0 {
 		c.Port = DefaultPort
 	}
+	if c.TFDownloadURL == "" {
+		c.TFDownloadURL = DefaultTFDownloadURL
+	}
 	if c.TFEHostname == "" {
 		c.TFEHostname = DefaultTFEHostname
 	}
diff --git a/cmd/server_test.go b/cmd/server_test.go
index fdf5efed95..c7fe501855 100644
--- a/cmd/server_test.go
+++ b/cmd/server_test.go
@@ -392,6 +392,7 @@ func TestExecute_Defaults(t *testing.T) {
 	Equals(t, "", passedConfig.SlackToken)
 	Equals(t, "", passedConfig.SSLCertFile)
 	Equals(t, "", passedConfig.SSLKeyFile)
+	Equals(t, "https://releases.hashicorp.com", passedConfig.TFDownloadURL)
 	Equals(t, "app.terraform.io", passedConfig.TFEHostname)
 	Equals(t, "", passedConfig.TFEToken)
 	Equals(t, false, passedConfig.WriteGitCreds)
@@ -515,6 +516,7 @@ func TestExecute_Flags(t *testing.T) {
 		cmd.SlackTokenFlag:             "slack-token",
 		cmd.SSLCertFileFlag:            "cert-file",
 		cmd.SSLKeyFileFlag:             "key-file",
+		cmd.TFDownloadURLFlag:          "https://my-hostname.com",
 		cmd.TFEHostnameFlag:            "my-hostname",
 		cmd.TFETokenFlag:               "my-token",
 		cmd.WriteGitCredsFlag:          true,
@@ -554,6 +556,7 @@ func TestExecute_Flags(t *testing.T) {
 	Equals(t, "slack-token", passedConfig.SlackToken)
 	Equals(t, "cert-file", passedConfig.SSLCertFile)
 	Equals(t, "key-file", passedConfig.SSLKeyFile)
+	Equals(t, "https://my-hostname.com", passedConfig.TFDownloadURL)
 	Equals(t, "my-hostname", passedConfig.TFEHostname)
 	Equals(t, "my-token", passedConfig.TFEToken)
 	Equals(t, true, passedConfig.WriteGitCreds)
@@ -594,6 +597,7 @@ require-mergeable: true
 slack-token: slack-token
 ssl-cert-file: cert-file
 ssl-key-file: key-file
+tf-download-url: https://my-hostname.com
 tfe-hostname: my-hostname
 tfe-token: my-token
 write-git-creds: true
@@ -637,6 +641,7 @@ write-git-creds: true
 	Equals(t, "slack-token", passedConfig.SlackToken)
 	Equals(t, "cert-file", passedConfig.SSLCertFile)
 	Equals(t, "key-file", passedConfig.SSLKeyFile)
+	Equals(t, "https://my-hostname.com", passedConfig.TFDownloadURL)
 	Equals(t, "my-hostname", passedConfig.TFEHostname)
 	Equals(t, "my-token", passedConfig.TFEToken)
 	Equals(t, true, passedConfig.WriteGitCreds)
@@ -676,6 +681,7 @@ require-approval: true
 slack-token: slack-token
 ssl-cert-file: cert-file
 ssl-key-file: key-file
+tf-download-url: https://my-hostname.com
 tfe-hostname: my-hostname
 tfe-token: my-token
 write-git-creds: true
@@ -716,6 +722,7 @@ write-git-creds: true
 		"SLACK_TOKEN":                  "override-slack-token",
 		"SSL_CERT_FILE":                "override-cert-file",
 		"SSL_KEY_FILE":                 "override-key-file",
+		"TF_DOWNLOAD_URL":              "https://override-my-hostname.com",
 		"TFE_HOSTNAME":                 "override-my-hostname",
 		"TFE_TOKEN":                    "override-my-token",
 		"WRITE_GIT_CREDS":              "false",
@@ -759,6 +766,7 @@ write-git-creds: true
 	Equals(t, "override-slack-token", passedConfig.SlackToken)
 	Equals(t, "override-cert-file", passedConfig.SSLCertFile)
 	Equals(t, "override-key-file", passedConfig.SSLKeyFile)
+	Equals(t, "https://override-my-hostname.com", passedConfig.TFDownloadURL)
 	Equals(t, "override-my-hostname", passedConfig.TFEHostname)
 	Equals(t, "override-my-token", passedConfig.TFEToken)
 	Equals(t, false, passedConfig.WriteGitCreds)
@@ -799,6 +807,7 @@ require-mergeable: true
 slack-token: slack-token
 ssl-cert-file: cert-file
 ssl-key-file: key-file
+tf-download-url: https://my-hostname.com
 tfe-hostname: my-hostname
 tfe-token: my-token
 write-git-creds: true
@@ -838,6 +847,7 @@ write-git-creds: true
 		cmd.SlackTokenFlag:             "override-slack-token",
 		cmd.SSLCertFileFlag:            "override-cert-file",
 		cmd.SSLKeyFileFlag:             "override-key-file",
+		cmd.TFDownloadURLFlag:          "https://override-my-hostname.com",
 		cmd.TFEHostnameFlag:            "override-my-hostname",
 		cmd.TFETokenFlag:               "override-my-token",
 		cmd.WriteGitCredsFlag:          false,
@@ -875,6 +885,7 @@ write-git-creds: true
 	Equals(t, "override-slack-token", passedConfig.SlackToken)
 	Equals(t, "override-cert-file", passedConfig.SSLCertFile)
 	Equals(t, "override-key-file", passedConfig.SSLKeyFile)
+	Equals(t, "https://override-my-hostname.com", passedConfig.TFDownloadURL)
 	Equals(t, "override-my-hostname", passedConfig.TFEHostname)
 	Equals(t, "override-my-token", passedConfig.TFEToken)
 	Equals(t, false, passedConfig.WriteGitCreds)
@@ -917,6 +928,7 @@ func TestExecute_FlagEnvVarOverride(t *testing.T) {
 		"SLACK_TOKEN":                  "slack-token",
 		"SSL_CERT_FILE":                "cert-file",
 		"SSL_KEY_FILE":                 "key-file",
+		"TF_DOWNLOAD_URL":              "https://my-hostname.com",
 		"TFE_HOSTNAME":                 "my-hostname",
 		"TFE_TOKEN":                    "my-token",
 		"WRITE_GIT_CREDS":              "true",
@@ -964,6 +976,7 @@ func TestExecute_FlagEnvVarOverride(t *testing.T) {
 		cmd.SlackTokenFlag:             "override-slack-token",
 		cmd.SSLCertFileFlag:            "override-cert-file",
 		cmd.SSLKeyFileFlag:             "override-key-file",
+		cmd.TFDownloadURLFlag:          "https://override-my-hostname.com",
 		cmd.TFEHostnameFlag:            "override-my-hostname",
 		cmd.TFETokenFlag:               "override-my-token",
 		cmd.WriteGitCredsFlag:          false,
@@ -1003,6 +1016,7 @@ func TestExecute_FlagEnvVarOverride(t *testing.T) {
 	Equals(t, "override-slack-token", passedConfig.SlackToken)
 	Equals(t, "override-cert-file", passedConfig.SSLCertFile)
 	Equals(t, "override-key-file", passedConfig.SSLKeyFile)
+	Equals(t, "https://override-my-hostname.com", passedConfig.TFDownloadURL)
 	Equals(t, "override-my-hostname", passedConfig.TFEHostname)
 	Equals(t, "override-my-token", passedConfig.TFEToken)
 	Equals(t, false, passedConfig.WriteGitCreds)
diff --git a/runatlantis.io/docs/server-configuration.md b/runatlantis.io/docs/server-configuration.md
index a48fd87ee4..6ebe9d7c67 100644
--- a/runatlantis.io/docs/server-configuration.md
+++ b/runatlantis.io/docs/server-configuration.md
@@ -421,7 +421,15 @@ Values are chosen in this order:
   atlantis server --ssl-cert-file="/etc/ssl/private/my-cert.key"
   ```
   File containing x509 private key matching `--ssl-cert-file`.
- 
+
+* ### `--tf-download-url`
+  ```bash
+  atlantis server --tf-download-url="https://releases.company.com"
+  ```
+  An alternative URL to download Terraform Versions if they are missing. Useful in an airgapped
+  environment where releases.hashicorp.com is not available. Directory structure of the custom
+  endpoint should match that of releases.hashicorp.com.
+
 * ### `--tfe-hostname`
   ```bash
   atlantis server --tfe-hostname="my-terraform-enterprise.company.com"
diff --git a/server/events/terraform/terraform_client.go b/server/events/terraform/terraform_client.go
index 8d7b448205..c0ff2b86e3 100644
--- a/server/events/terraform/terraform_client.go
+++ b/server/events/terraform/terraform_client.go
@@ -56,7 +56,8 @@ type DefaultClient struct {
 	// with another binary, ex. echo.
 	overrideTF string
 	// downloader downloads terraform versions.
-	downloader Downloader
+	downloader  Downloader
+	downloadURL string
 	// versions maps from the string representation of a tf version (ex. 0.11.10)
 	// to the absolute path of that binary on disk (if it exists).
 	// Use versionsLock to control access.
@@ -80,8 +81,6 @@ const (
 	// binDirName is the name of the directory inside our data dir where
 	// we download terraform binaries.
 	binDirName = "bin"
-	// releasesURL is the base url to download terraform from.
-	releasesURL = "https://releases.hashicorp.com"
 )
 
 // versionRegex extracts the version from `terraform version` output.
@@ -107,6 +106,7 @@ func NewClient(
 	tfeHostname string,
 	defaultVersionStr string,
 	defaultVersionFlagName string,
+	tfDownloadURL string,
 	tfDownloader Downloader) (*DefaultClient, error) {
 	var finalDefaultVersion *version.Version
 	var localVersion *version.Version
@@ -145,7 +145,7 @@ func NewClient(
 			// Since ensureVersion might end up downloading terraform,
 			// we call it asynchronously so as to not delay server startup.
 			versionsLock.Lock()
-			_, err := ensureVersion(log, tfDownloader, versions, defaultVersion, binDir)
+			_, err := ensureVersion(log, tfDownloader, versions, defaultVersion, binDir, tfDownloadURL)
 			versionsLock.Unlock()
 			if err != nil {
 				log.Err("could not download terraform %s", defaultVersion.String())
@@ -176,6 +176,7 @@ func NewClient(
 		terraformPluginCacheDir: cacheDir,
 		binDir:                  binDir,
 		downloader:              tfDownloader,
+		downloadURL:             tfDownloadURL,
 		versionsLock:            &versionsLock,
 		versions:                versions,
 	}, nil
@@ -192,6 +193,11 @@ func (c *DefaultClient) TerraformBinDir() string {
 	return c.binDir
 }
 
+//TerraformDownloadURL returns the URL where we download Terraform binaries.
+func (c *DefaultClient) TerraformDownloadURL() string {
+	return c.downloadURL
+}
+
 // See Client.EnsureVersion.
 func (c *DefaultClient) EnsureVersion(log *logging.SimpleLogger, v *version.Version) error {
 	if v == nil {
@@ -200,7 +206,7 @@ func (c *DefaultClient) EnsureVersion(log *logging.SimpleLogger, v *version.Vers
 
 	var err error
 	c.versionsLock.Lock()
-	_, err = ensureVersion(log, c.downloader, c.versions, v, c.binDir)
+	_, err = ensureVersion(log, c.downloader, c.versions, v, c.binDir, c.downloadURL)
 	c.versionsLock.Unlock()
 	if err != nil {
 		return err
@@ -245,7 +251,7 @@ func (c *DefaultClient) prepCmd(log *logging.SimpleLogger, v *version.Version, w
 	} else {
 		var err error
 		c.versionsLock.Lock()
-		binPath, err = ensureVersion(log, c.downloader, c.versions, v, c.binDir)
+		binPath, err = ensureVersion(log, c.downloader, c.versions, v, c.binDir, c.downloadURL)
 		c.versionsLock.Unlock()
 		if err != nil {
 			return "", nil, err
@@ -390,7 +396,7 @@ func MustConstraint(v string) version.Constraints {
 
 // ensureVersion returns the path to a terraform binary of version v.
 // It will download this version if we don't have it.
-func ensureVersion(log *logging.SimpleLogger, dl Downloader, versions map[string]string, v *version.Version, binDir string) (string, error) {
+func ensureVersion(log *logging.SimpleLogger, dl Downloader, versions map[string]string, v *version.Version, binDir string, downloadURL string) (string, error) {
 	if binPath, ok := versions[v.String()]; ok {
 		return binPath, nil
 	}
@@ -411,9 +417,8 @@ func ensureVersion(log *logging.SimpleLogger, dl Downloader, versions map[string
 		versions[v.String()] = dest
 		return dest, nil
 	}
-
-	log.Info("could not find terraform version %s in PATH or %s, downloading from %s", v.String(), binDir, releasesURL)
-	urlPrefix := fmt.Sprintf("%s/terraform/%s/terraform_%s", releasesURL, v.String(), v.String())
+	log.Info("could not find terraform version %s in PATH or %s, downloading from %s", v.String(), binDir, downloadURL)
+	urlPrefix := fmt.Sprintf("%s/terraform/%s/terraform_%s", downloadURL, v.String(), v.String())
 	binURL := fmt.Sprintf("%s_%s_%s.zip", urlPrefix, runtime.GOOS, runtime.GOARCH)
 	checksumURL := fmt.Sprintf("%s_SHA256SUMS", urlPrefix)
 	if err := dl.GetFile(dest, fmt.Sprintf("%s?checksum=file:%s", binURL, checksumURL)); err != nil {
diff --git a/server/events/terraform/terraform_client_test.go b/server/events/terraform/terraform_client_test.go
index 39bcb85940..0293ed579d 100644
--- a/server/events/terraform/terraform_client_test.go
+++ b/server/events/terraform/terraform_client_test.go
@@ -68,7 +68,7 @@ is 0.11.13. You can update by downloading from www.terraform.io/downloads.html
 	Ok(t, err)
 	defer tempSetEnv(t, "PATH", fmt.Sprintf("%s:%s", tmp, os.Getenv("PATH")))()
 
-	c, err := terraform.NewClient(nil, tmp, "", "", "", cmd.DefaultTFVersionFlag, nil)
+	c, err := terraform.NewClient(nil, tmp, "", "", "", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	Ok(t, err)
 
 	Ok(t, err)
@@ -96,7 +96,7 @@ is 0.11.13. You can update by downloading from www.terraform.io/downloads.html
 	Ok(t, err)
 	defer tempSetEnv(t, "PATH", fmt.Sprintf("%s:%s", tmp, os.Getenv("PATH")))()
 
-	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, nil)
+	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	Ok(t, err)
 
 	Ok(t, err)
@@ -116,7 +116,7 @@ func TestNewClient_NoTF(t *testing.T) {
 	// Set PATH to only include our empty directory.
 	defer tempSetEnv(t, "PATH", tmp)()
 
-	_, err := terraform.NewClient(nil, tmp, "", "", "", cmd.DefaultTFVersionFlag, nil)
+	_, err := terraform.NewClient(nil, tmp, "", "", "", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	ErrEquals(t, "terraform not found in $PATH. Set --default-tf-version or download terraform from https://www.terraform.io/downloads.html", err)
 }
 
@@ -133,7 +133,7 @@ func TestNewClient_DefaultTFFlagInPath(t *testing.T) {
 	Ok(t, err)
 	defer tempSetEnv(t, "PATH", fmt.Sprintf("%s:%s", tmp, os.Getenv("PATH")))()
 
-	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, nil)
+	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	Ok(t, err)
 
 	Ok(t, err)
@@ -157,7 +157,7 @@ func TestNewClient_DefaultTFFlagInBinDir(t *testing.T) {
 	Ok(t, err)
 	defer tempSetEnv(t, "PATH", fmt.Sprintf("%s:%s", tmp, os.Getenv("PATH")))()
 
-	c, err := terraform.NewClient(logging.NewNoopLogger(), tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, nil)
+	c, err := terraform.NewClient(logging.NewNoopLogger(), tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	Ok(t, err)
 
 	Ok(t, err)
@@ -183,12 +183,12 @@ func TestNewClient_DefaultTFFlagDownload(t *testing.T) {
 		err := ioutil.WriteFile(params[0].(string), []byte("#!/bin/sh\necho '\nTerraform v0.11.10\n'"), 0755)
 		return []pegomock.ReturnValue{err}
 	})
-	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, mockDownloader)
+	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, mockDownloader)
 	Ok(t, err)
 
 	Ok(t, err)
 	Equals(t, "0.11.10", c.DefaultVersion().String())
-	baseURL := "https://releases.hashicorp.com/terraform/0.11.10"
+	baseURL := fmt.Sprintf("%s/terraform/0.11.10", cmd.TFDownloadURLFlag)
 	expURL := fmt.Sprintf("%s/terraform_0.11.10_%s_%s.zip?checksum=file:%s/terraform_0.11.10_SHA256SUMS",
 		baseURL,
 		runtime.GOOS,
@@ -207,7 +207,7 @@ func TestNewClient_DefaultTFFlagDownload(t *testing.T) {
 func TestNewClient_BadVersion(t *testing.T) {
 	tmp, cleanup := TempDir(t)
 	defer cleanup()
-	_, err := terraform.NewClient(nil, tmp, "", "", "malformed", cmd.DefaultTFVersionFlag, nil)
+	_, err := terraform.NewClient(nil, tmp, "", "", "malformed", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, nil)
 	ErrEquals(t, "Malformed version: malformed", err)
 }
 
@@ -219,7 +219,7 @@ func TestRunCommandWithVersion_DLsTF(t *testing.T) {
 
 	mockDownloader := mocks.NewMockDownloader()
 	// Set up our mock downloader to write a fake tf binary when it's called.
-	baseURL := "https://releases.hashicorp.com/terraform/99.99.99"
+	baseURL := fmt.Sprintf("%s/terraform/99.99.99", cmd.TFDownloadURLFlag)
 	expURL := fmt.Sprintf("%s/terraform_99.99.99_%s_%s.zip?checksum=file:%s/terraform_99.99.99_SHA256SUMS",
 		baseURL,
 		runtime.GOOS,
@@ -230,7 +230,7 @@ func TestRunCommandWithVersion_DLsTF(t *testing.T) {
 		return []pegomock.ReturnValue{err}
 	})
 
-	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, mockDownloader)
+	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, mockDownloader)
 	Ok(t, err)
 	Equals(t, "0.11.10", c.DefaultVersion().String())
 
@@ -249,7 +249,7 @@ func TestEnsureVersion_downloaded(t *testing.T) {
 
 	mockDownloader := mocks.NewMockDownloader()
 
-	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, mockDownloader)
+	c, err := terraform.NewClient(nil, tmp, "", "", "0.11.10", cmd.DefaultTFVersionFlag, cmd.TFDownloadURLFlag, mockDownloader)
 	Ok(t, err)
 
 	Equals(t, "0.11.10", c.DefaultVersion().String())
@@ -261,7 +261,7 @@ func TestEnsureVersion_downloaded(t *testing.T) {
 
 	Ok(t, err)
 
-	baseURL := "https://releases.hashicorp.com/terraform/99.99.99"
+	baseURL := fmt.Sprintf("%s/terraform/99.99.99", cmd.TFDownloadURLFlag)
 	expURL := fmt.Sprintf("%s/terraform_99.99.99_%s_%s.zip?checksum=file:%s/terraform_99.99.99_SHA256SUMS",
 		baseURL,
 		runtime.GOOS,
diff --git a/server/events_controller_e2e_test.go b/server/events_controller_e2e_test.go
index 4332bc2849..275d2a9fd9 100644
--- a/server/events_controller_e2e_test.go
+++ b/server/events_controller_e2e_test.go
@@ -400,7 +400,7 @@ func setupE2E(t *testing.T, repoDir string) (server.EventsController, *vcsmocks.
 		GithubUser: "github-user",
 		GitlabUser: "gitlab-user",
 	}
-	terraformClient, err := terraform.NewClient(logger, dataDir, "", "", "", "default-tf-version", &NoopTFDownloader{})
+	terraformClient, err := terraform.NewClient(logger, dataDir, "", "", "", "tfdownloadurl", "default-tf-version", &NoopTFDownloader{})
 	Ok(t, err)
 	boltdb, err := db.New(dataDir)
 	Ok(t, err)
diff --git a/server/server.go b/server/server.go
index 7a9c4f3941..bec83a7784 100644
--- a/server/server.go
+++ b/server/server.go
@@ -211,6 +211,7 @@ func NewServer(userConfig UserConfig, config Config) (*Server, error) {
 		userConfig.DataDir,
 		userConfig.TFEToken,
 		userConfig.TFEHostname,
+		userConfig.TFDownloadURL,
 		userConfig.DefaultTFVersion,
 		config.DefaultTFVersionFlag,
 		&terraform.DefaultDownloader{})
diff --git a/server/user_config.go b/server/user_config.go
index b3c101f27c..a40614afe4 100644
--- a/server/user_config.go
+++ b/server/user_config.go
@@ -44,6 +44,7 @@ type UserConfig struct {
 	SlackToken             string          `mapstructure:"slack-token"`
 	SSLCertFile            string          `mapstructure:"ssl-cert-file"`
 	SSLKeyFile             string          `mapstructure:"ssl-key-file"`
+	TFDownloadURL          string          `mapstructure:"tf-download-url"`
 	TFEHostname            string          `mapstructure:"tfe-hostname"`
 	TFEToken               string          `mapstructure:"tfe-token"`
 	DefaultTFVersion       string          `mapstructure:"default-tf-version"`