diff --git a/api/queries_pr.go b/api/queries_pr.go
index be86dc679..b2e5f2f77 100644
--- a/api/queries_pr.go
+++ b/api/queries_pr.go
@@ -340,7 +340,7 @@ func PullRequestByNumber(client *Client, repo ghrepo.Interface, number int) (*Pu
 	return &resp.Repository.PullRequest, nil
 }
 
-func PullRequestForBranch(client *Client, repo ghrepo.Interface, branch string) (*PullRequest, error) {
+func PullRequestForBranch(client *Client, repo ghrepo.Interface, baseBranch, headBranch string) (*PullRequest, error) {
 	type response struct {
 		Repository struct {
 			PullRequests struct {
@@ -376,9 +376,9 @@ func PullRequestForBranch(client *Client, repo ghrepo.Interface, branch string)
 		}
 	}`
 
-	branchWithoutOwner := branch
-	if idx := strings.Index(branch, ":"); idx >= 0 {
-		branchWithoutOwner = branch[idx+1:]
+	branchWithoutOwner := headBranch
+	if idx := strings.Index(headBranch, ":"); idx >= 0 {
+		branchWithoutOwner = headBranch[idx+1:]
 	}
 
 	variables := map[string]interface{}{
@@ -394,12 +394,17 @@ func PullRequestForBranch(client *Client, repo ghrepo.Interface, branch string)
 	}
 
 	for _, pr := range resp.Repository.PullRequests.Nodes {
-		if pr.HeadLabel() == branch {
+		if pr.HeadLabel() == headBranch {
+			if baseBranch != "" {
+				if pr.BaseRefName != baseBranch {
+					continue
+				}
+			}
 			return &pr, nil
 		}
 	}
 
-	return nil, &NotFoundError{fmt.Errorf("no open pull requests found for branch %q", branch)}
+	return nil, &NotFoundError{fmt.Errorf("no open pull requests found for branch %q", headBranch)}
 }
 
 // CreatePullRequest creates a pull request in a GitHub repository
diff --git a/api/queries_repo.go b/api/queries_repo.go
index 048b72b50..ea2862500 100644
--- a/api/queries_repo.go
+++ b/api/queries_repo.go
@@ -154,7 +154,7 @@ func RepoNetwork(client *Client, repos []ghrepo.Interface) (RepoNetworkResult, e
 		keys = append(keys, key)
 	}
 	// sort keys to ensure `repo_{N}` entries are processed in order
-	sort.Sort(sort.StringSlice(keys))
+	sort.Strings(keys)
 
 	// Iterate over keys of GraphQL response data and, based on its name,
 	// dynamically allocate the target struct an individual message gets decoded to.
diff --git a/command/pr.go b/command/pr.go
index aa22464f4..03a9a5627 100644
--- a/command/pr.go
+++ b/command/pr.go
@@ -255,9 +255,21 @@ func prView(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	baseRepo, err := determineBaseRepo(cmd, ctx)
-	if err != nil {
-		return err
+	var baseRepo ghrepo.Interface
+	var prArg string
+	if len(args) > 0 {
+		prArg = args[0]
+		if prNum, repo := prFromURL(prArg); repo != nil {
+			prArg = prNum
+			baseRepo = repo
+		}
+	}
+
+	if baseRepo == nil {
+		baseRepo, err = determineBaseRepo(cmd, ctx)
+		if err != nil {
+			return err
+		}
 	}
 
 	preview, err := cmd.Flags().GetBool("preview")
@@ -268,7 +280,7 @@ func prView(cmd *cobra.Command, args []string) error {
 	var openURL string
 	var pr *api.PullRequest
 	if len(args) > 0 {
-		pr, err = prFromArg(apiClient, baseRepo, args[0])
+		pr, err = prFromArg(apiClient, baseRepo, prArg)
 		if err != nil {
 			return err
 		}
@@ -288,7 +300,7 @@ func prView(cmd *cobra.Command, args []string) error {
 				}
 			}
 		} else {
-			pr, err = api.PullRequestForBranch(apiClient, baseRepo, branchWithOwner)
+			pr, err = api.PullRequestForBranch(apiClient, baseRepo, "", branchWithOwner)
 			if err != nil {
 				return err
 			}
@@ -331,17 +343,19 @@ func printPrPreview(out io.Writer, pr *api.PullRequest) error {
 
 var prURLRE = regexp.MustCompile(`^https://github\.com/([^/]+)/([^/]+)/pull/(\d+)`)
 
+func prFromURL(arg string) (string, ghrepo.Interface) {
+	if m := prURLRE.FindStringSubmatch(arg); m != nil {
+		return m[3], ghrepo.New(m[1], m[2])
+	}
+	return "", nil
+}
+
 func prFromArg(apiClient *api.Client, baseRepo ghrepo.Interface, arg string) (*api.PullRequest, error) {
 	if prNumber, err := strconv.Atoi(strings.TrimPrefix(arg, "#")); err == nil {
 		return api.PullRequestByNumber(apiClient, baseRepo, prNumber)
 	}
 
-	if m := prURLRE.FindStringSubmatch(arg); m != nil {
-		prNumber, _ := strconv.Atoi(m[3])
-		return api.PullRequestByNumber(apiClient, baseRepo, prNumber)
-	}
-
-	return api.PullRequestForBranch(apiClient, baseRepo, arg)
+	return api.PullRequestForBranch(apiClient, baseRepo, "", arg)
 }
 
 func prSelectorForCurrentBranch(ctx context.Context, baseRepo ghrepo.Interface) (prNumber int, prHeadRef string, err error) {
diff --git a/command/pr_checkout.go b/command/pr_checkout.go
index 08a37033d..336a5a8d1 100644
--- a/command/pr_checkout.go
+++ b/command/pr_checkout.go
@@ -7,6 +7,7 @@ import (
 	"os/exec"
 
 	"github.com/cli/cli/git"
+	"github.com/cli/cli/internal/ghrepo"
 	"github.com/cli/cli/utils"
 	"github.com/spf13/cobra"
 )
@@ -18,21 +19,38 @@ func prCheckout(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
-	// FIXME: duplicates logic from fsContext.BaseRepo
-	baseRemote, err := remotes.FindByName("upstream", "github", "origin", "*")
-	if err != nil {
-		return err
-	}
+
 	apiClient, err := apiClientForContext(ctx)
 	if err != nil {
 		return err
 	}
 
-	pr, err := prFromArg(apiClient, baseRemote, args[0])
+	var baseRepo ghrepo.Interface
+	prArg := args[0]
+	if prNum, repo := prFromURL(prArg); repo != nil {
+		prArg = prNum
+		baseRepo = repo
+	}
+
+	if baseRepo == nil {
+		baseRepo, err = determineBaseRepo(cmd, ctx)
+		if err != nil {
+			return err
+		}
+	}
+
+	pr, err := prFromArg(apiClient, baseRepo, prArg)
 	if err != nil {
 		return err
 	}
 
+	baseRemote, _ := remotes.FindByRepo(baseRepo.RepoOwner(), baseRepo.RepoName())
+	// baseRemoteSpec is a repository URL or a remote name to be used in git fetch
+	baseURLOrName := fmt.Sprintf("https://github.com/%s.git", ghrepo.FullName(baseRepo))
+	if baseRemote != nil {
+		baseURLOrName = baseRemote.Name
+	}
+
 	headRemote := baseRemote
 	if pr.IsCrossRepository {
 		headRemote, _ = remotes.FindByRepo(pr.HeadRepositoryOwner.Login, pr.HeadRepository.Name)
@@ -67,15 +85,15 @@ func prCheckout(cmd *cobra.Command, args []string) error {
 		ref := fmt.Sprintf("refs/pull/%d/head", pr.Number)
 		if newBranchName == currentBranch {
 			// PR head matches currently checked out branch
-			cmdQueue = append(cmdQueue, []string{"git", "fetch", baseRemote.Name, ref})
+			cmdQueue = append(cmdQueue, []string{"git", "fetch", baseURLOrName, ref})
 			cmdQueue = append(cmdQueue, []string{"git", "merge", "--ff-only", "FETCH_HEAD"})
 		} else {
 			// create a new branch
-			cmdQueue = append(cmdQueue, []string{"git", "fetch", baseRemote.Name, fmt.Sprintf("%s:%s", ref, newBranchName)})
+			cmdQueue = append(cmdQueue, []string{"git", "fetch", baseURLOrName, fmt.Sprintf("%s:%s", ref, newBranchName)})
 			cmdQueue = append(cmdQueue, []string{"git", "checkout", newBranchName})
 		}
 
-		remote := baseRemote.Name
+		remote := baseURLOrName
 		mergeRef := ref
 		if pr.MaintainerCanModify {
 			remote = fmt.Sprintf("https://github.com/%s/%s.git", pr.HeadRepositoryOwner.Login, pr.HeadRepository.Name)
diff --git a/command/pr_checkout_test.go b/command/pr_checkout_test.go
index ce0266c5e..1a36756a7 100644
--- a/command/pr_checkout_test.go
+++ b/command/pr_checkout_test.go
@@ -2,6 +2,8 @@ package command
 
 import (
 	"bytes"
+	"encoding/json"
+	"io/ioutil"
 	"os/exec"
 	"strings"
 	"testing"
@@ -21,6 +23,7 @@ func TestPRCheckout_sameRepo(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -112,6 +115,68 @@ func TestPRCheckout_urlArg(t *testing.T) {
 	eq(t, strings.Join(ranCommands[1], " "), "git checkout -b feature --no-track origin/feature")
 }
 
+func TestPRCheckout_urlArg_differentBase(t *testing.T) {
+	ctx := context.NewBlank()
+	ctx.SetBranch("master")
+	ctx.SetRemotes(map[string]string{
+		"origin": "OWNER/REPO",
+	})
+	initContext = func() context.Context {
+		return ctx
+	}
+	http := initFakeHTTP()
+
+	http.StubResponse(200, bytes.NewBufferString(`
+	{ "data": { "repository": { "pullRequest": {
+		"number": 123,
+		"headRefName": "feature",
+		"headRepositoryOwner": {
+			"login": "hubot"
+		},
+		"headRepository": {
+			"name": "POE",
+			"defaultBranchRef": {
+				"name": "master"
+			}
+		},
+		"isCrossRepository": false,
+		"maintainerCanModify": false
+	} } } }
+	`))
+
+	ranCommands := [][]string{}
+	restoreCmd := utils.SetPrepareCmd(func(cmd *exec.Cmd) utils.Runnable {
+		switch strings.Join(cmd.Args, " ") {
+		case "git show-ref --verify --quiet refs/heads/feature":
+			return &errorStub{"exit status: 1"}
+		default:
+			ranCommands = append(ranCommands, cmd.Args)
+			return &test.OutputStub{}
+		}
+	})
+	defer restoreCmd()
+
+	output, err := RunCommand(prCheckoutCmd, `pr checkout https://github.com/OTHER/POE/pull/123/files`)
+	eq(t, err, nil)
+	eq(t, output.String(), "")
+
+	bodyBytes, _ := ioutil.ReadAll(http.Requests[0].Body)
+	reqBody := struct {
+		Variables struct {
+			Owner string
+			Repo  string
+		}
+	}{}
+	json.Unmarshal(bodyBytes, &reqBody)
+
+	eq(t, reqBody.Variables.Owner, "OTHER")
+	eq(t, reqBody.Variables.Repo, "POE")
+
+	eq(t, len(ranCommands), 5)
+	eq(t, strings.Join(ranCommands[1], " "), "git fetch https://github.com/OTHER/POE.git refs/pull/123/head:feature")
+	eq(t, strings.Join(ranCommands[3], " "), "git config branch.feature.remote https://github.com/OTHER/POE.git")
+}
+
 func TestPRCheckout_branchArg(t *testing.T) {
 	ctx := context.NewBlank()
 	ctx.SetBranch("master")
@@ -122,6 +187,7 @@ func TestPRCheckout_branchArg(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequests": { "nodes": [
@@ -171,6 +237,7 @@ func TestPRCheckout_existingBranch(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -223,6 +290,7 @@ func TestPRCheckout_differentRepo_remoteExists(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -275,6 +343,7 @@ func TestPRCheckout_differentRepo(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -327,6 +396,7 @@ func TestPRCheckout_differentRepo_existingBranch(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -377,6 +447,7 @@ func TestPRCheckout_differentRepo_currentBranch(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
@@ -427,6 +498,7 @@ func TestPRCheckout_maintainerCanModify(t *testing.T) {
 		return ctx
 	}
 	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
diff --git a/command/pr_create.go b/command/pr_create.go
index ca7800a19..2be922987 100644
--- a/command/pr_create.go
+++ b/command/pr_create.go
@@ -132,13 +132,13 @@ func prCreate(cmd *cobra.Command, _ []string) error {
 		if headRepo != nil && !ghrepo.IsSame(baseRepo, headRepo) {
 			headBranchLabel = fmt.Sprintf("%s:%s", headRepo.RepoOwner(), headBranch)
 		}
-		existingPR, err := api.PullRequestForBranch(client, baseRepo, headBranchLabel)
+		existingPR, err := api.PullRequestForBranch(client, baseRepo, baseBranch, headBranchLabel)
 		var notFound *api.NotFoundError
 		if err != nil && !errors.As(err, &notFound) {
 			return fmt.Errorf("error checking for existing pull request: %w", err)
 		}
 		if err == nil {
-			return fmt.Errorf("a pull request for branch %q already exists:\n%s", headBranchLabel, existingPR.URL)
+			return fmt.Errorf("a pull request for branch %q into branch %q already exists:\n%s", headBranchLabel, baseBranch, existingPR.URL)
 		}
 	}
 
diff --git a/command/pr_create_test.go b/command/pr_create_test.go
index 688dfd9c8..874b02a86 100644
--- a/command/pr_create_test.go
+++ b/command/pr_create_test.go
@@ -64,7 +64,8 @@ func TestPRCreate_alreadyExists(t *testing.T) {
 	http.StubResponse(200, bytes.NewBufferString(`
 		{ "data": { "repository": { "pullRequests": { "nodes": [
 			{ "url": "https://github.com/OWNER/REPO/pull/123",
-			  "headRefName": "feature" }
+			  "headRefName": "feature",
+				"baseRefName": "master" }
 		] } } } }
 	`))
 
@@ -78,11 +79,37 @@ func TestPRCreate_alreadyExists(t *testing.T) {
 	if err == nil {
 		t.Fatal("error expected, got nil")
 	}
-	if err.Error() != "a pull request for branch \"feature\" already exists:\nhttps://github.com/OWNER/REPO/pull/123" {
+	if err.Error() != "a pull request for branch \"feature\" into branch \"master\" already exists:\nhttps://github.com/OWNER/REPO/pull/123" {
 		t.Errorf("got error %q", err)
 	}
 }
 
+func TestPRCreate_alreadyExistsDifferentBase(t *testing.T) {
+	initBlankContext("OWNER/REPO", "feature")
+	http := initFakeHTTP()
+	http.StubRepoResponse("OWNER", "REPO")
+	http.StubResponse(200, bytes.NewBufferString(`
+		{ "data": { "repository": { "pullRequests": { "nodes": [
+			{ "url": "https://github.com/OWNER/REPO/pull/123",
+			  "headRefName": "feature",
+				"baseRefName": "master" }
+		] } } } }
+	`))
+	http.StubResponse(200, bytes.NewBufferString("{}"))
+
+	cs, cmdTeardown := initCmdStubber()
+	defer cmdTeardown()
+
+	cs.Stub("")                                         // git status
+	cs.Stub("1234567890,commit 0\n2345678901,commit 1") // git log
+	cs.Stub("")                                         // git rev-parse
+
+	_, err := RunCommand(prCreateCmd, `pr create -BanotherBase -t"cool" -b"nah"`)
+	if err != nil {
+		t.Errorf("got unexpected error %q", err)
+	}
+}
+
 func TestPRCreate_web(t *testing.T) {
 	initBlankContext("OWNER/REPO", "feature")
 	http := initFakeHTTP()
diff --git a/command/pr_test.go b/command/pr_test.go
index 9fda8980c..505aff77d 100644
--- a/command/pr_test.go
+++ b/command/pr_test.go
@@ -635,7 +635,6 @@ func TestPRView_numberArgWithHash(t *testing.T) {
 func TestPRView_urlArg(t *testing.T) {
 	initBlankContext("OWNER/REPO", "master")
 	http := initFakeHTTP()
-	http.StubRepoResponse("OWNER", "REPO")
 
 	http.StubResponse(200, bytes.NewBufferString(`
 	{ "data": { "repository": { "pullRequest": {
diff --git a/command/repo.go b/command/repo.go
index 1dc9b13a5..be930c0c8 100644
--- a/command/repo.go
+++ b/command/repo.go
@@ -295,7 +295,7 @@ func repoFork(cmd *cobra.Command, args []string) error {
 
 	greenCheck := utils.Green("✓")
 	out := colorableOut(cmd)
-	s := utils.Spinner()
+	s := utils.Spinner(out)
 	loading := utils.Gray("Forking ") + utils.Bold(utils.Gray(ghrepo.FullName(toFork))) + utils.Gray("...")
 	s.Suffix = " " + loading
 	s.FinalMSG = utils.Gray(fmt.Sprintf("- %s\n", loading))
diff --git a/go.mod b/go.mod
index 63a39c1bf..ee45df4ed 100644
--- a/go.mod
+++ b/go.mod
@@ -5,7 +5,7 @@ go 1.13
 require (
 	github.com/AlecAivazis/survey/v2 v2.0.7
 	github.com/briandowns/spinner v1.9.0
-	github.com/charmbracelet/glamour v0.1.1-0.20200304134224-7e5c90143acc
+	github.com/charmbracelet/glamour v0.1.1-0.20200320173916-301d3bcf3058
 	github.com/dlclark/regexp2 v1.2.0 // indirect
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/hashicorp/go-version v1.2.0
diff --git a/go.sum b/go.sum
index 8d7665e96..b94236621 100644
--- a/go.sum
+++ b/go.sum
@@ -23,8 +23,8 @@ github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+Ce
 github.com/briandowns/spinner v1.9.0 h1:+OMAisemaHar1hjuJ3Z2hIvNhQl9Y7GLPWUwwz2Pxo8=
 github.com/briandowns/spinner v1.9.0/go.mod h1://Zf9tMcxfRUA36V23M6YGEAv+kECGfvpnLTnb8n4XQ=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
-github.com/charmbracelet/glamour v0.1.1-0.20200304134224-7e5c90143acc h1:WSZ06evYgfSZYqkcv0+jFVSVCJeYsIvU+J4ILZUrha4=
-github.com/charmbracelet/glamour v0.1.1-0.20200304134224-7e5c90143acc/go.mod h1:sC1EP6T+3nFnl5vwf0TYEs1inMigQxZ7n912YKoxJow=
+github.com/charmbracelet/glamour v0.1.1-0.20200320173916-301d3bcf3058 h1:Ks+RZ6s6UriHnL+yusm3OoaLwpV9WPvMV+FXQ6qMD7M=
+github.com/charmbracelet/glamour v0.1.1-0.20200320173916-301d3bcf3058/go.mod h1:sC1EP6T+3nFnl5vwf0TYEs1inMigQxZ7n912YKoxJow=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/coreos/bbolt v1.3.2/go.mod h1:iRUV2dpdMOn7Bo10OQBFzIJO9kkE559Wcmn+qkEiiKk=
 github.com/coreos/etcd v3.3.10+incompatible/go.mod h1:uF7uidLiAD3TWHmW31ZFd/JWoc32PjwdhPthX9715RE=
diff --git a/pkg/githubtemplate/github_template.go b/pkg/githubtemplate/github_template.go
index f60878725..3aac35554 100644
--- a/pkg/githubtemplate/github_template.go
+++ b/pkg/githubtemplate/github_template.go
@@ -59,7 +59,7 @@ mainLoop:
 		}
 	}
 
-	sort.Sort(sort.StringSlice(results))
+	sort.Strings(results)
 	return results
 }
 
diff --git a/utils/utils.go b/utils/utils.go
index 6217871b7..77c643eba 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -2,6 +2,7 @@ package utils
 
 import (
 	"fmt"
+	"io"
 	"strings"
 	"time"
 
@@ -68,6 +69,8 @@ func Humanize(s string) string {
 	return strings.Map(h, s)
 }
 
-func Spinner() *spinner.Spinner {
-	return spinner.New(spinner.CharSets[11], 400*time.Millisecond)
+func Spinner(w io.Writer) *spinner.Spinner {
+	s := spinner.New(spinner.CharSets[11], 400*time.Millisecond)
+	s.Writer = w
+	return s
 }