diff --git a/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..fdafb3b7ac341
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/quebec.rs
@@ -0,0 +1,5 @@
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/tango.rs
new file mode 100644
index 0000000000000..ff12fe98d82c2
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/auxiliary/tango.rs
@@ -0,0 +1,8 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/sierra.rs b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/sierra.rs
new file mode 100644
index 0000000000000..665f9567ba2d2
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/cargo-transitive-read-write/sierra.rs
@@ -0,0 +1,25 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ has quebec/struct.Quebec.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// similar to cargo-workflow-transitive, but we use --merge=read-write,
+// which is the default.
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..d10bc0316ccad
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/quebec.rs
@@ -0,0 +1,7 @@
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/romeo.rs b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/romeo.rs
new file mode 100644
index 0000000000000..6d0c8651db53f
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/romeo.rs
@@ -0,0 +1,10 @@
+//@ aux-build:sierra.rs
+//@ build-aux-docs
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/romeo
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate sierra;
+pub type Romeo = sierra::Sierra;
diff --git a/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/sierra.rs b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/sierra.rs
new file mode 100644
index 0000000000000..10898f3886477
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/sierra.rs
@@ -0,0 +1,11 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/sierra
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/tango.rs
new file mode 100644
index 0000000000000..3c3721ee6eb7d
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/auxiliary/tango.rs
@@ -0,0 +1,10 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/indigo.rs b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/indigo.rs
new file mode 100644
index 0000000000000..f03f6bd6026fa
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/kitchen-sink-separate-dirs/indigo.rs
@@ -0,0 +1,35 @@
+//@ aux-build:tango.rs
+//@ aux-build:romeo.rs
+//@ aux-build:quebec.rs
+//@ aux-build:sierra.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--include-parts-dir=info/doc.parts/tango
+//@ doc-flags:--include-parts-dir=info/doc.parts/romeo
+//@ doc-flags:--include-parts-dir=info/doc.parts/quebec
+//@ doc-flags:--include-parts-dir=info/doc.parts/sierra
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html
+//@ has index.html '//ul[@class="all-items"]//a[@href="indigo/index.html"]' 'indigo'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has index.html '//ul[@class="all-items"]//a[@href="romeo/index.html"]' 'romeo'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ !has quebec/struct.Quebec.html
+//@ !has romeo/type.Romeo.html
+//@ !has sierra/struct.Sierra.html
+//@ !has tango/trait.Tango.html
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Quebec'
+//@ hasraw search-index.js 'Romeo'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Tango'
+//@ has type.impl/sierra/struct.Sierra.js
+//@ hasraw type.impl/sierra/struct.Sierra.js 'Tango'
+//@ hasraw type.impl/sierra/struct.Sierra.js 'Romeo'
+
+// document everything in the default mode, there are separate out
+// directories that are linked together
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..61210529fa6bc
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/quebec.rs
@@ -0,0 +1,6 @@
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/tango.rs
new file mode 100644
index 0000000000000..70d8a4b91f549
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/auxiliary/tango.rs
@@ -0,0 +1,9 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-separate/sierra.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/sierra.rs
new file mode 100644
index 0000000000000..7eac207e51886
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-separate/sierra.rs
@@ -0,0 +1,17 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ !has index.html
+//@ has sierra/struct.Sierra.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ !has trait.impl/tango/trait.Tango.js
+//@ !has search-index.js
+
+// we don't generate any cross-crate info if --merge=none, even if we
+// document crates separately
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..6ab921533b037
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/quebec.rs
@@ -0,0 +1,6 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/tango.rs
new file mode 100644
index 0000000000000..9fa99d3be8af4
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/auxiliary/tango.rs
@@ -0,0 +1,9 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/sierra.rs b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/sierra.rs
new file mode 100644
index 0000000000000..f3340a80c848b
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/no-merge-write-anyway/sierra.rs
@@ -0,0 +1,18 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/sierra
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ !has index.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ !has trait.impl/tango/trait.Tango.js
+//@ !has search-index.js
+
+// we --merge=none, so --parts-out-dir doesn't do anything
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..6ab921533b037
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/quebec.rs
@@ -0,0 +1,6 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/tango.rs
new file mode 100644
index 0000000000000..9fa99d3be8af4
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/auxiliary/tango.rs
@@ -0,0 +1,9 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/sierra.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/sierra.rs
new file mode 100644
index 0000000000000..8eb0f1d049831
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-include/sierra.rs
@@ -0,0 +1,22 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--include-parts-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has quebec/struct.Quebec.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ !hasraw search-index.js 'Quebec'
+
+// we overwrite quebec and tango's cross-crate information, but we
+// include the info from tango meaning that it should appear in the out
+// dir
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..d10bc0316ccad
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/quebec.rs
@@ -0,0 +1,7 @@
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/tango.rs
new file mode 100644
index 0000000000000..3c3721ee6eb7d
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/auxiliary/tango.rs
@@ -0,0 +1,10 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ unique-doc-out-dir
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/sierra.rs b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/sierra.rs
new file mode 100644
index 0000000000000..4ee036238b4b1
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite-but-separate/sierra.rs
@@ -0,0 +1,25 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--include-parts-dir=info/doc.parts/tango
+//@ doc-flags:--include-parts-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ has sierra/struct.Sierra.html
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// If these were documeted into the same directory, the info would be
+// overwritten. However, since they are merged, we can still recover all
+// of the cross-crate information
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..0e28d8e646647
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/quebec.rs
@@ -0,0 +1,5 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/tango.rs
new file mode 100644
index 0000000000000..363b2d5508e63
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite/auxiliary/tango.rs
@@ -0,0 +1,8 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/overwrite/sierra.rs b/tests/rustdoc/merge-cross-crate-info/overwrite/sierra.rs
new file mode 100644
index 0000000000000..11e61dd2744b6
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/overwrite/sierra.rs
@@ -0,0 +1,20 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has quebec/struct.Quebec.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ !hasraw search-index.js 'Quebec'
+
+// since tango is documented with --merge=finalize, we overwrite q's
+// cross-crate information
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/single-crate-finalize/quebec.rs b/tests/rustdoc/merge-cross-crate-info/single-crate-finalize/quebec.rs
new file mode 100644
index 0000000000000..09bb78c06f1c2
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/single-crate-finalize/quebec.rs
@@ -0,0 +1,13 @@
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has quebec/struct.Quebec.html
+//@ hasraw search-index.js 'Quebec'
+
+// there is nothing to read from the output directory if we use a single
+// crate
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/single-crate-read-write/quebec.rs b/tests/rustdoc/merge-cross-crate-info/single-crate-read-write/quebec.rs
new file mode 100644
index 0000000000000..72475426f6edd
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/single-crate-read-write/quebec.rs
@@ -0,0 +1,12 @@
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has quebec/struct.Quebec.html
+//@ hasraw search-index.js 'Quebec'
+
+// read-write is the default and this does the same as `single-crate`
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/single-crate-write-anyway/quebec.rs b/tests/rustdoc/merge-cross-crate-info/single-crate-write-anyway/quebec.rs
new file mode 100644
index 0000000000000..b20e173a8307e
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/single-crate-write-anyway/quebec.rs
@@ -0,0 +1,13 @@
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has quebec/struct.Quebec.html
+//@ hasraw search-index.js 'Quebec'
+
+// we can --parts-out-dir, but that doesn't do anything other than create
+// the file
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/single-merge-none-useless-write/quebec.rs b/tests/rustdoc/merge-cross-crate-info/single-merge-none-useless-write/quebec.rs
new file mode 100644
index 0000000000000..e888a43c46042
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/single-merge-none-useless-write/quebec.rs
@@ -0,0 +1,11 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ !has index.html
+//@ has quebec/struct.Quebec.html
+//@ !has search-index.js
+
+// --merge=none doesn't write anything, despite --parts-out-dir
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..1beca543f814f
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/quebec.rs
@@ -0,0 +1,5 @@
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/tango.rs
new file mode 100644
index 0000000000000..363b2d5508e63
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/auxiliary/tango.rs
@@ -0,0 +1,8 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-finalize/sierra.rs b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/sierra.rs
new file mode 100644
index 0000000000000..68fc4b13fa8f7
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-finalize/sierra.rs
@@ -0,0 +1,20 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Sierra'
+
+// write only overwrites stuff in the output directory
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..6ab921533b037
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/quebec.rs
@@ -0,0 +1,6 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/tango.rs
new file mode 100644
index 0000000000000..9fa99d3be8af4
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/auxiliary/tango.rs
@@ -0,0 +1,9 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--parts-out-dir=info/doc.parts/tango
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/sierra.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/sierra.rs
new file mode 100644
index 0000000000000..b407228085e88
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-none/sierra.rs
@@ -0,0 +1,27 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--include-parts-dir=info/doc.parts/tango
+//@ doc-flags:--include-parts-dir=info/doc.parts/quebec
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ has quebec/struct.Quebec.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// We avoid writing any cross-crate information, preferring to include it
+// with --include-parts-dir.
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..1beca543f814f
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/quebec.rs
@@ -0,0 +1,5 @@
+//@ doc-flags:--merge=finalize
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/tango.rs
new file mode 100644
index 0000000000000..ff12fe98d82c2
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/auxiliary/tango.rs
@@ -0,0 +1,8 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/sierra.rs b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/sierra.rs
new file mode 100644
index 0000000000000..15e32d5941fb2
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-merge-read-write/sierra.rs
@@ -0,0 +1,25 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=shared
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="quebec/index.html"]' 'quebec'
+//@ has index.html '//ul[@class="all-items"]//a[@href="sierra/index.html"]' 'sierra'
+//@ has index.html '//ul[@class="all-items"]//a[@href="tango/index.html"]' 'tango'
+//@ has quebec/struct.Quebec.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/tango/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// We can use read-write to emulate the default behavior of rustdoc, when
+// --merge is left out.
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/quebec.rs b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/quebec.rs
new file mode 100644
index 0000000000000..0e28d8e646647
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/quebec.rs
@@ -0,0 +1,5 @@
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/tango.rs b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/tango.rs
new file mode 100644
index 0000000000000..3827119f696f5
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/auxiliary/tango.rs
@@ -0,0 +1,8 @@
+//@ aux-build:quebec.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate quebec;
+pub trait Tango {}
diff --git a/tests/rustdoc/merge-cross-crate-info/transitive-no-info/sierra.rs b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/sierra.rs
new file mode 100644
index 0000000000000..3eb2cebd74363
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/transitive-no-info/sierra.rs
@@ -0,0 +1,17 @@
+//@ aux-build:tango.rs
+//@ build-aux-docs
+//@ doc-flags:--merge=none
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ !has index.html
+//@ has sierra/struct.Sierra.html
+//@ has tango/trait.Tango.html
+//@ hasraw sierra/struct.Sierra.html 'Tango'
+//@ !has trait.impl/tango/trait.Tango.js
+//@ !has search-index.js
+
+// --merge=none on all crates does not generate any cross-crate info
+extern crate tango;
+pub struct Sierra;
+impl tango::Tango for Sierra {}
diff --git a/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/auxiliary/foxtrot.rs b/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/auxiliary/foxtrot.rs
new file mode 100644
index 0000000000000..e492b700dbc2b
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/auxiliary/foxtrot.rs
@@ -0,0 +1,5 @@
+//@ unique-doc-out-dir
+//@ doc-flags:--parts-out-dir=info/doc.parts/foxtrot
+//@ doc-flags:-Zunstable-options
+
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/echo.rs b/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/echo.rs
new file mode 100644
index 0000000000000..ee2b646e43cda
--- /dev/null
+++ b/tests/rustdoc/merge-cross-crate-info/two-separate-out-dir/echo.rs
@@ -0,0 +1,16 @@
+//@ aux-build:foxtrot.rs
+//@ build-aux-docs
+//@ doc-flags:--include-parts-dir=info/doc.parts/foxtrot
+//@ doc-flags:-Zunstable-options
+
+//@ has echo/enum.Echo.html
+//@ hasraw echo/enum.Echo.html 'Foxtrot'
+//@ hasraw trait.impl/foxtrot/trait.Foxtrot.js 'enum.Echo.html'
+//@ hasraw search-index.js 'Foxtrot'
+//@ hasraw search-index.js 'Echo'
+
+// document two crates in different places, and merge their docs after
+// they are generated
+extern crate foxtrot;
+pub enum Echo {}
+impl foxtrot::Foxtrot for Echo {}