diff --git a/aws/resource_aws_spot_fleet_request.go b/aws/resource_aws_spot_fleet_request.go
index cadbe2d15bd..6864097ee62 100644
--- a/aws/resource_aws_spot_fleet_request.go
+++ b/aws/resource_aws_spot_fleet_request.go
@@ -294,7 +294,7 @@ func resourceAwsSpotFleetRequest() *schema.Resource {
 			},
 			"spot_price": {
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
 				ForceNew: true,
 			},
 			"terminate_instances_with_expiration": {
diff --git a/aws/resource_aws_spot_fleet_request_test.go b/aws/resource_aws_spot_fleet_request_test.go
index c4982a46933..f259c52dc97 100644
--- a/aws/resource_aws_spot_fleet_request_test.go
+++ b/aws/resource_aws_spot_fleet_request_test.go
@@ -312,6 +312,31 @@ func TestAccAWSSpotFleetRequest_overriddingSpotPrice(t *testing.T) {
 	})
 }
 
+func TestAccAWSSpotFleetRequest_withoutSpotPrice(t *testing.T) {
+	var sfr ec2.SpotFleetRequestConfig
+	rName := acctest.RandString(10)
+	rInt := acctest.RandInt()
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSSpotFleetRequestDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSSpotFleetRequestConfigWithoutSpotPrice(rName, rInt),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckAWSSpotFleetRequestExists(
+						"aws_spot_fleet_request.foo", &sfr),
+					resource.TestCheckResourceAttr(
+						"aws_spot_fleet_request.foo", "spot_request_state", "active"),
+					resource.TestCheckResourceAttr(
+						"aws_spot_fleet_request.foo", "launch_specification.#", "2"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSSpotFleetRequest_diversifiedAllocation(t *testing.T) {
 	var sfr ec2.SpotFleetRequestConfig
 	rName := acctest.RandString(10)
@@ -1511,6 +1536,87 @@ resource "aws_spot_fleet_request" "foo" {
 `, rName, rInt, rInt, rName)
 }
 
+func testAccAWSSpotFleetRequestConfigWithoutSpotPrice(rName string, rInt int) string {
+	return fmt.Sprintf(`
+resource "aws_key_pair" "debugging" {
+	key_name = "tmp-key-%s"
+	public_key = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQD3F6tyPEFEzV0LX3X8BsXdMsQz1x2cEikKDEY0aIj41qgxMCP/iteneqXSIFZBp5vizPvaoIR3Um9xK7PGoW8giupGn+EPuxIA4cDM4vzOqOkiMPhz5XK0whEjkVzTo4+S0puvDZuwIsdiW9mxhJc7tgBNL0cYlWSYVkz4G/fslNfRPW5mYAM49f4fhtxPb5ok4Q2Lg9dPKVHO/Bgeu5woMc7RY0p1ej6D4CKFE6lymSDJpW0YHX/wqE9+cfEauh7xZcG0q9t2ta6F6fmX0agvpFyZo8aFbXeUBr7osSCJNgvavWbM/06niWrOvYX2xwWdhXmXSrbX8ZbabVohBK41 phodgson@thoughtworks.com"
+}
+
+resource "aws_iam_policy" "test-policy" {
+  name = "test-policy-%d"
+  path = "/"
+  description = "Spot Fleet Request ACCTest Policy"
+  policy = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [{
+    "Effect": "Allow",
+    "Action": [
+       "ec2:DescribeImages",
+       "ec2:DescribeSubnets",
+       "ec2:RequestSpotInstances",
+       "ec2:TerminateInstances",
+       "ec2:DescribeInstanceStatus",
+       "iam:PassRole"
+        ],
+    "Resource": ["*"]
+  }]
+}
+EOF
+}
+
+resource "aws_iam_policy_attachment" "test-attach" {
+    name = "test-attachment-%d"
+    roles = ["${aws_iam_role.test-role.name}"]
+    policy_arn = "${aws_iam_policy.test-policy.arn}"
+}
+
+resource "aws_iam_role" "test-role" {
+    name = "test-role-%s"
+    assume_role_policy = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Sid": "",
+      "Effect": "Allow",
+      "Principal": {
+        "Service": [
+          "spotfleet.amazonaws.com",
+          "ec2.amazonaws.com"
+        ]
+      },
+      "Action": "sts:AssumeRole"
+    }
+  ]
+}
+EOF
+}
+
+resource "aws_spot_fleet_request" "foo" {
+    iam_fleet_role = "${aws_iam_role.test-role.arn}"
+    target_capacity = 2
+    valid_until = "2019-11-04T20:44:20Z"
+    terminate_instances_with_expiration = true
+    wait_for_fulfillment = true
+    launch_specification {
+        instance_type = "m1.small"
+        ami = "ami-516b9131"
+        key_name = "${aws_key_pair.debugging.key_name}"
+        availability_zone = "us-west-2a"
+    }
+    launch_specification {
+        instance_type = "m3.large"
+        ami = "ami-d06a90b0"
+        key_name = "${aws_key_pair.debugging.key_name}"
+        availability_zone = "us-west-2a"
+    }
+    depends_on = ["aws_iam_policy_attachment.test-attach"]
+}
+`, rName, rInt, rInt, rName)
+}
+
 func testAccAWSSpotFleetRequestConfigDiversifiedAllocation(rName string, rInt int) string {
 	return fmt.Sprintf(`
 resource "aws_key_pair" "debugging" {
diff --git a/aws/resource_aws_spot_instance_request.go b/aws/resource_aws_spot_instance_request.go
index a3d566d6872..5a0dbeabc84 100644
--- a/aws/resource_aws_spot_instance_request.go
+++ b/aws/resource_aws_spot_instance_request.go
@@ -44,7 +44,7 @@ func resourceAwsSpotInstanceRequest() *schema.Resource {
 
 			s["spot_price"] = &schema.Schema{
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
 				ForceNew: true,
 			}
 			s["spot_type"] = &schema.Schema{
diff --git a/aws/resource_aws_spot_instance_request_test.go b/aws/resource_aws_spot_instance_request_test.go
index 2a79a74733f..09d82f71e48 100644
--- a/aws/resource_aws_spot_instance_request_test.go
+++ b/aws/resource_aws_spot_instance_request_test.go
@@ -152,6 +152,31 @@ func TestAccAWSSpotInstanceRequest_validUntil(t *testing.T) {
 	})
 }
 
+func TestAccAWSSpotInstanceRequest_withoutSpotPrice(t *testing.T) {
+	var sir ec2.SpotInstanceRequest
+	rInt := acctest.RandInt()
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSSpotInstanceRequestDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSSpotInstanceRequestConfig_withoutSpotPrice(rInt),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSSpotInstanceRequestExists(
+						"aws_spot_instance_request.foo", &sir),
+					testAccCheckAWSSpotInstanceRequestAttributesCheckSIRWithoutSpot(&sir),
+					resource.TestCheckResourceAttr(
+						"aws_spot_instance_request.foo", "spot_bid_status", "fulfilled"),
+					resource.TestCheckResourceAttr(
+						"aws_spot_instance_request.foo", "spot_request_state", "active"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSSpotInstanceRequest_SubnetAndSGAndPublicIpAddress(t *testing.T) {
 	var sir ec2.SpotInstanceRequest
 	rInt := acctest.RandInt()
@@ -374,6 +399,19 @@ func testAccCheckAWSSpotInstanceRequestAttributesValidUntil(
 	}
 }
 
+func testAccCheckAWSSpotInstanceRequestAttributesCheckSIRWithoutSpot(
+	sir *ec2.SpotInstanceRequest) resource.TestCheckFunc {
+	return func(s *terraform.State) error {
+		if *sir.State != "active" {
+			return fmt.Errorf("Unexpected request state: %s", *sir.State)
+		}
+		if *sir.Status.Code != "fulfilled" {
+			return fmt.Errorf("Unexpected bid status: %s", *sir.State)
+		}
+		return nil
+	}
+}
+
 func testAccCheckAWSSpotInstanceRequest_InstanceAttributes(
 	sir *ec2.SpotInstanceRequest, rInt int) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
@@ -547,6 +585,30 @@ func testAccAWSSpotInstanceRequestConfigValidUntil(rInt int, validUntil string)
 	}`, rInt, validUntil)
 }
 
+func testAccAWSSpotInstanceRequestConfig_withoutSpotPrice(rInt int) string {
+	return fmt.Sprintf(`
+	resource "aws_key_pair" "debugging" {
+		key_name = "tmp-key-%d"
+		public_key = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQD3F6tyPEFEzV0LX3X8BsXdMsQz1x2cEikKDEY0aIj41qgxMCP/iteneqXSIFZBp5vizPvaoIR3Um9xK7PGoW8giupGn+EPuxIA4cDM4vzOqOkiMPhz5XK0whEjkVzTo4+S0puvDZuwIsdiW9mxhJc7tgBNL0cYlWSYVkz4G/fslNfRPW5mYAM49f4fhtxPb5ok4Q2Lg9dPKVHO/Bgeu5woMc7RY0p1ej6D4CKFE6lymSDJpW0YHX/wqE9+cfEauh7xZcG0q9t2ta6F6fmX0agvpFyZo8aFbXeUBr7osSCJNgvavWbM/06niWrOvYX2xwWdhXmXSrbX8ZbabVohBK41 phodgson@thoughtworks.com"
+	}
+
+	resource "aws_spot_instance_request" "foo" {
+		ami = "ami-4fccb37f"
+		instance_type = "m1.small"
+		key_name = "${aws_key_pair.debugging.key_name}"
+
+		# no spot price so AWS *should* default max bid to current on-demand price
+
+		# we wait for fulfillment because we want to inspect the launched instance
+		# and verify termination behavior
+		wait_for_fulfillment = true
+
+		tags {
+			Name = "terraform-test"
+		}
+	}`, rInt)
+}
+
 func testAccAWSSpotInstanceRequestConfig_withLaunchGroup(rInt int) string {
 	return fmt.Sprintf(`
 	resource "aws_key_pair" "debugging" {
diff --git a/website/docs/r/launch_configuration.html.markdown b/website/docs/r/launch_configuration.html.markdown
index 2177c67cf1d..5865e1ce6ef 100644
--- a/website/docs/r/launch_configuration.html.markdown
+++ b/website/docs/r/launch_configuration.html.markdown
@@ -158,7 +158,7 @@ The following arguments are supported:
   instance.  See [Block Devices](#block-devices) below for details.
 * `ephemeral_block_device` - (Optional) Customize Ephemeral (also known as
   "Instance Store") volumes on the instance. See [Block Devices](#block-devices) below for details.
-* `spot_price` - (Optional) The price to use for reserving spot instances.
+* `spot_price` - (Optional; Default: On-demand price) The maximum price to use for reserving spot instances.
 * `placement_tenancy` - (Optional) The tenancy of the instance. Valid values are
   `"default"` or `"dedicated"`, see [AWS's Create Launch Configuration](http://docs.aws.amazon.com/AutoScaling/latest/APIReference/API_CreateLaunchConfiguration.html)
   for more details
diff --git a/website/docs/r/spot_fleet_request.html.markdown b/website/docs/r/spot_fleet_request.html.markdown
index 2dd9ef095b4..52a9f3751c3 100644
--- a/website/docs/r/spot_fleet_request.html.markdown
+++ b/website/docs/r/spot_fleet_request.html.markdown
@@ -97,7 +97,7 @@ across different markets and instance types.
     what you can specify. See the list of officially supported inputs in the
     [reference documentation](http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_SpotFleetLaunchSpecification.html). Any normal [`aws_instance`](instance.html) parameter that corresponds to those inputs may be used.
 
-* `spot_price` - (Required) The bid price per unit hour.
+* `spot_price` - (Optional; Default: On-demand price) The maximum bid price per unit hour.
 * `wait_for_fulfillment` - (Optional; Default: false) If set, Terraform will
   wait for the Spot Request to be fulfilled, and will throw an error if the
   timeout of 10m is reached.
diff --git a/website/docs/r/spot_instance_request.html.markdown b/website/docs/r/spot_instance_request.html.markdown
index b866cd3b3ad..0819fec0e77 100644
--- a/website/docs/r/spot_instance_request.html.markdown
+++ b/website/docs/r/spot_instance_request.html.markdown
@@ -48,7 +48,7 @@ resource "aws_spot_instance_request" "cheap_worker" {
 Spot Instance Requests support all the same arguments as
 [`aws_instance`](instance.html), with the addition of:
 
-* `spot_price` - (Required) The price to request on the spot market.
+* `spot_price` - (Optional; Default: On-demand price) The maximum price to request on the spot market.
 * `wait_for_fulfillment` - (Optional; Default: false) If set, Terraform will
   wait for the Spot Request to be fulfilled, and will throw an error if the
   timeout of 10m is reached.