diff --git a/src/cmd/go/internal/modget/get.go b/src/cmd/go/internal/modget/get.go
index 06d59d9..4ca7f5b 100644
--- a/src/cmd/go/internal/modget/get.go
+++ b/src/cmd/go/internal/modget/get.go
@@ -702,6 +702,15 @@
 	// Everything succeeded. Update go.mod.
 	modload.AllowWriteGoMod()
 	modload.WriteGoMod()
+	modload.DisallowWriteGoMod()
+
+	// Report warnings if any retracted versions are in the build list.
+	// This must be done after writing go.mod to avoid spurious '// indirect'
+	// comments. These functions read and write global state.
+	// TODO(golang.org/issue/40775): ListModules resets modload.loader, which
+	// contains information about direct dependencies that WriteGoMod uses.
+	// Refactor to avoid these kinds of global side effects.
+	reportRetractions(ctx)
 
 	// If -d was specified, we're done after the module work.
 	// We've already downloaded modules by loading packages above.
@@ -804,6 +813,14 @@
 		base.Fatalf("go get: internal error: prevM may be set if and only if forceModulePath is set")
 	}
 
+	// If vers is a query like "latest", we should ignore retracted and excluded
+	// versions. If vers refers to a specific version or commit like "v1.0.0"
+	// or "master", we should only ignore excluded versions.
+	allowed := modload.CheckAllowed
+	if modload.IsRevisionQuery(vers) {
+		allowed = modload.CheckExclusions
+	}
+
 	// If the query must be a module path, try only that module path.
 	if forceModulePath {
 		if path == modload.Target.Path {
@@ -812,7 +829,7 @@
 			}
 		}
 
-		info, err := modload.Query(ctx, path, vers, prevM.Version, modload.CheckAllowed)
+		info, err := modload.Query(ctx, path, vers, prevM.Version, allowed)
 		if err == nil {
 			if info.Version != vers && info.Version != prevM.Version {
 				logOncef("go: %s %s => %s", path, vers, info.Version)
@@ -838,7 +855,7 @@
 	// If it turns out to only exist as a module, we can detect the resulting
 	// PackageNotInModuleError and avoid a second round-trip through (potentially)
 	// all of the configured proxies.
-	results, err := modload.QueryPattern(ctx, path, vers, modload.CheckAllowed)
+	results, err := modload.QueryPattern(ctx, path, vers, allowed)
 	if err != nil {
 		// If the path doesn't contain a wildcard, check whether it was actually a
 		// module path instead. If so, return that.
@@ -1050,6 +1067,43 @@
 	return r.Reqs.Required(mod)
 }
 
+// reportRetractions prints warnings if any modules in the build list are
+// retracted.
+func reportRetractions(ctx context.Context) {
+	// Query for retractions of modules in the build list.
+	// Use modload.ListModules, since that provides information in the same format
+	// as 'go list -m'. Don't query for "all", since that's not allowed outside a
+	// module.
+	buildList := modload.BuildList()
+	args := make([]string, 0, len(buildList))
+	for _, m := range buildList {
+		if m.Version == "" {
+			// main module or dummy target module
+			continue
+		}
+		args = append(args, m.Path+"@"+m.Version)
+	}
+	listU := false
+	listVersions := false
+	listRetractions := true
+	mods := modload.ListModules(ctx, args, listU, listVersions, listRetractions)
+	retractPath := ""
+	for _, mod := range mods {
+		if len(mod.Retracted) > 0 {
+			if retractPath == "" {
+				retractPath = mod.Path
+			} else {
+				retractPath = "<module>"
+			}
+			rationale := modload.ShortRetractionRationale(mod.Retracted[0])
+			logOncef("go: warning: %s@%s is retracted: %s", mod.Path, mod.Version, rationale)
+		}
+	}
+	if modload.HasModRoot() && retractPath != "" {
+		logOncef("go: run 'go get %s@latest' to switch to the latest unretracted version", retractPath)
+	}
+}
+
 var loggedLines sync.Map
 
 func logOncef(format string, args ...interface{}) {
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-block.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-block.txt
new file mode 100644
index 0000000..c4a53e1
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-block.txt
@@ -0,0 +1,6 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-block"}
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-blockwithcomment.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-blockwithcomment.txt
new file mode 100644
index 0000000..92573b6
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-blockwithcomment.txt
@@ -0,0 +1,6 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-blockwithcomment"}
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-empty.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-empty.txt
new file mode 100644
index 0000000..1f0894a
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-empty.txt
@@ -0,0 +1,8 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-empty"}
+-- empty.go --
+package empty
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-long.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-long.txt
new file mode 100644
index 0000000..1b5e753
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-long.txt
@@ -0,0 +1,8 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-long"}
+-- empty.go --
+package empty
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline1.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline1.txt
new file mode 100644
index 0000000..b1ffe27
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline1.txt
@@ -0,0 +1,8 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-multiline1"}
+-- empty.go --
+package empty
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline2.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline2.txt
new file mode 100644
index 0000000..72f80b3
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-multiline2.txt
@@ -0,0 +1,8 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-multiline2"}
+-- empty.go --
+package empty
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-order.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-order.txt
new file mode 100644
index 0000000..1b04504
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-order.txt
@@ -0,0 +1,6 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-order"}
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-unprintable.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-unprintable.txt
new file mode 100644
index 0000000..9496124
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.0-unprintable.txt
@@ -0,0 +1,8 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.0-unprintable"}
+-- empty.go --
+package empty
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.1-order.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.1-order.txt
new file mode 100644
index 0000000..3be7d5b
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.0.1-order.txt
@@ -0,0 +1,6 @@
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+-- .info --
+{"Version":"v1.0.1-order"}
diff --git a/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.9.0.txt b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.9.0.txt
new file mode 100644
index 0000000..6975d4e
--- /dev/null
+++ b/src/cmd/go/testdata/mod/example.com_retract_rationale_v1.9.0.txt
@@ -0,0 +1,48 @@
+Module example.com/retract/description retracts all versions of itself.
+The rationale comments have various problems.
+
+-- .mod --
+module example.com/retract/rationale
+
+go 1.14
+
+retract (
+	v1.0.0-empty
+
+	// short description
+	// more
+	//
+	// detail
+	v1.0.0-multiline1 // suffix
+	// after not included
+)
+
+// short description
+// more
+//
+// detail
+retract v1.0.0-multiline2 // suffix
+
+// loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong
+retract v1.0.0-long
+
+// Ends with a BEL character. Beep!
+retract v1.0.0-unprintable
+
+// block comment
+retract (
+	v1.0.0-block
+
+	// inner comment
+	v1.0.0-blockwithcomment
+)
+
+retract (
+	[v1.0.0-order, v1.0.0-order] // degenerate range
+	v1.0.0-order // single version
+
+	v1.0.1-order // single version
+	[v1.0.1-order, v1.0.1-order] // degenerate range
+)
+-- .info --
+{"Version":"v1.9.0"}
diff --git a/src/cmd/go/testdata/script/mod_get_retract.txt b/src/cmd/go/testdata/script/mod_get_retract.txt
new file mode 100644
index 0000000..da6c255
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_get_retract.txt
@@ -0,0 +1,49 @@
+# 'go get pkg' should not upgrade to a retracted version.
+cp go.mod.orig go.mod
+go mod edit -require example.com/retract/self/prev@v1.1.0
+go get -d example.com/retract/self/prev
+go list -m example.com/retract/self/prev
+stdout '^example.com/retract/self/prev v1.1.0$'
+
+# 'go get pkg' should not downgrade from a retracted version when no higher
+# version is available.
+cp go.mod.orig go.mod
+go mod edit -require example.com/retract/self/prev@v1.9.0
+go get -d example.com/retract/self/prev
+stderr '^go: warning: example.com/retract/self/prev@v1.9.0 is retracted: self$'
+go list -m example.com/retract/self/prev
+stdout '^example.com/retract/self/prev v1.9.0$'
+
+# 'go get pkg@latest' should downgrade from a retracted version.
+cp go.mod.orig go.mod
+go mod edit -require example.com/retract/self/prev@v1.9.0
+go get -d example.com/retract/self/prev@latest
+go list -m example.com/retract/self/prev
+stdout '^example.com/retract/self/prev v1.1.0$'
+
+# 'go get pkg@version' should update to a specific version, even if that
+# version is retracted.
+cp go.mod.orig go.mod
+go get -d example.com/retract@v1.0.0-bad
+stderr '^go: warning: example.com/retract@v1.0.0-bad is retracted: bad$'
+go list -m example.com/retract
+stdout '^example.com/retract v1.0.0-bad$'
+
+# 'go get -u' should not downgrade from a retracted version when no higher
+# version is available.
+cp go.mod.orig go.mod
+go mod edit -require example.com/retract/self/prev@v1.9.0
+go get -d -u .
+stderr '^go: warning: example.com/retract/self/prev@v1.9.0 is retracted: self$'
+go list -m example.com/retract/self/prev
+stdout '^example.com/retract/self/prev v1.9.0$'
+
+-- go.mod.orig --
+module example.com/use
+
+go 1.15
+
+-- use.go --
+package use
+
+import _ "example.com/retract/self/prev"
diff --git a/src/cmd/go/testdata/script/mod_retract_rationale.txt b/src/cmd/go/testdata/script/mod_retract_rationale.txt
new file mode 100644
index 0000000..584c3a3
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_retract_rationale.txt
@@ -0,0 +1,79 @@
+# When there is no rationale, 'go get' should print a hard-coded message.
+go get -d example.com/retract/rationale@v1.0.0-empty
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-empty is retracted: retracted by module author$'
+
+# 'go list' should print the same hard-coded message.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale
+stdout '^\[retracted by module author\]$'
+
+
+# When there is a multi-line message, 'go get' should print the first line.
+go get -d example.com/retract/rationale@v1.0.0-multiline1
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-multiline1 is retracted: short description$'
+! stderr 'detail'
+
+# 'go list' should show the full message.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale
+cmp stdout multiline
+
+# 'go get' output should be the same whether the retraction appears at top-level
+# or in a block.
+go get -d example.com/retract/rationale@v1.0.0-multiline2
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-multiline2 is retracted: short description$'
+! stderr 'detail'
+
+# Same for 'go list'.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale
+cmp stdout multiline
+
+
+# 'go get' should omit long messages.
+go get -d example.com/retract/rationale@v1.0.0-long
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-long is retracted: \(rationale omitted: too long\)'
+
+# 'go list' should show the full message.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale
+stdout '^\[lo{500}ng\]$'
+
+
+# 'go get' should omit messages with unprintable characters.
+go get -d example.com/retract/rationale@v1.0.0-unprintable
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-unprintable is retracted: \(rationale omitted: contains non-printable characters\)'
+
+# 'go list' should show the full message.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale
+stdout '^\[Ends with a BEL character. Beep!\x07\]$'
+
+
+# When there is a comment on a block, but not on individual retractions within
+# the block, the rationale should come from the block comment.
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale@v1.0.0-block
+stdout '^\[block comment\]$'
+go list -m -retracted -f '{{.Retracted}}' example.com/retract/rationale@v1.0.0-blockwithcomment
+stdout '^\[inner comment\]$'
+
+
+# When a version is covered by multiple retractions, all retractions should
+# be reported in the order they appear in the file.
+go list -m -retracted -f '{{range .Retracted}}{{.}},{{end}}' example.com/retract/rationale@v1.0.0-order
+stdout '^degenerate range,single version,$'
+go list -m -retracted -f '{{range .Retracted}}{{.}},{{end}}' example.com/retract/rationale@v1.0.1-order
+stdout '^single version,degenerate range,$'
+
+# 'go get' will only report the first retraction to avoid being too verbose.
+go get -d example.com/retract/rationale@v1.0.0-order
+stderr '^go: warning: example.com/retract/rationale@v1.0.0-order is retracted: degenerate range$'
+go get -d example.com/retract/rationale@v1.0.1-order
+stderr '^go: warning: example.com/retract/rationale@v1.0.1-order is retracted: single version$'
+
+-- go.mod --
+module m
+
+go 1.14
+
+-- multiline --
+[short description
+more
+
+detail
+suffix]