diff --git a/src/test/auxiliary/trait_superkinds_in_metadata.rs b/src/test/auxiliary/trait_superkinds_in_metadata.rs
index 02d2a6b8af4..dfb0c0310ec 100644
--- a/src/test/auxiliary/trait_superkinds_in_metadata.rs
+++ b/src/test/auxiliary/trait_superkinds_in_metadata.rs
@@ -8,7 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Test library crate for cross-crate usages of traits inheriting
+// from the builtin kinds. Mostly tests metadata correctness.
+
 #[crate_type="lib"];
 
-pub trait Bar : Freeze { }
-pub trait Foo : Bar + Send { }
+pub trait RequiresFreeze : Freeze { }
+pub trait RequiresRequiresFreezeAndSend : RequiresFreeze + Send { }
diff --git a/src/test/compile-fail/builtin-superkinds-double-superkind.rs b/src/test/compile-fail/builtin-superkinds-double-superkind.rs
index c5dbcd9bb23..15fa0b66433 100644
--- a/src/test/compile-fail/builtin-superkinds-double-superkind.rs
+++ b/src/test/compile-fail/builtin-superkinds-double-superkind.rs
@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Test for traits that inherit from multiple builtin kinds at once,
+// testing that all such kinds must be present on implementing types.
+
 trait Foo : Send+Freeze { }
 
 impl <T: Freeze> Foo for (T,) { } //~ ERROR cannot implement this trait
diff --git a/src/test/compile-fail/builtin-superkinds-in-metadata.rs b/src/test/compile-fail/builtin-superkinds-in-metadata.rs
index 3fa7c5a28ba..a52a3765889 100644
--- a/src/test/compile-fail/builtin-superkinds-in-metadata.rs
+++ b/src/test/compile-fail/builtin-superkinds-in-metadata.rs
@@ -10,13 +10,16 @@
 
 // aux-build:trait_superkinds_in_metadata.rs
 
+// Test for traits inheriting from the builtin kinds cross-crate.
+// Mostly tests correctness of metadata.
+
 extern mod trait_superkinds_in_metadata;
-use trait_superkinds_in_metadata::{Foo, Bar};
+use trait_superkinds_in_metadata::{RequiresRequiresFreezeAndSend, RequiresFreeze};
 
 struct X<T>(T);
 
-impl <T:Freeze> Bar for X<T> { }
+impl <T:Freeze> RequiresFreeze for X<T> { }
 
-impl <T:Freeze> Foo for X<T> { } //~ ERROR cannot implement this trait
+impl <T:Freeze> RequiresRequiresFreezeAndSend for X<T> { } //~ ERROR cannot implement this trait
 
 fn main() { }
diff --git a/src/test/compile-fail/builtin-superkinds-simple.rs b/src/test/compile-fail/builtin-superkinds-simple.rs
index 472bef715e9..c1011f1368a 100644
--- a/src/test/compile-fail/builtin-superkinds-simple.rs
+++ b/src/test/compile-fail/builtin-superkinds-simple.rs
@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Basic test for traits inheriting from the builtin kinds, checking
+// the type contents of the implementing type (that's not a typaram).
+
 trait Foo : Send { }
 
 impl <'self> Foo for &'self mut () { } //~ ERROR cannot implement this trait
diff --git a/src/test/compile-fail/builtin-superkinds-typaram-not-send.rs b/src/test/compile-fail/builtin-superkinds-typaram-not-send.rs
index ec10ba09104..2a3d3c7df61 100644
--- a/src/test/compile-fail/builtin-superkinds-typaram-not-send.rs
+++ b/src/test/compile-fail/builtin-superkinds-typaram-not-send.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Basic test for traits inheriting from the builtin kinds.
+
 trait Foo : Send { }
 
 impl <T: Freeze> Foo for T { } //~ ERROR cannot implement this trait
diff --git a/src/test/run-pass/builtin-superkinds-capabilities-transitive.rs b/src/test/run-pass/builtin-superkinds-capabilities-transitive.rs
index 8b9cd057457..ab5e58285d4 100644
--- a/src/test/run-pass/builtin-superkinds-capabilities-transitive.rs
+++ b/src/test/run-pass/builtin-superkinds-capabilities-transitive.rs
@@ -8,6 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Tests "transitivity" of super-builtin-kinds on traits. Here, if
+// we have a Foo, we know we have a Bar, and if we have a Bar, we
+// know we have a Send. So if we have a Foo we should know we have
+// a Send. Basically this just makes sure rustc is using
+// each_bound_trait_and_supertraits in type_contents correctly.
+
 trait Bar : Send { }
 trait Foo : Bar { }
 
diff --git a/src/test/run-pass/builtin-superkinds-capabilities-xc.rs b/src/test/run-pass/builtin-superkinds-capabilities-xc.rs
index 85012896253..1e24c121f5a 100644
--- a/src/test/run-pass/builtin-superkinds-capabilities-xc.rs
+++ b/src/test/run-pass/builtin-superkinds-capabilities-xc.rs
@@ -10,16 +10,19 @@
 
 // aux-build:trait_superkinds_in_metadata.rs
 
+// Tests "capabilities" granted by traits with super-builtin-kinds,
+// even when using them cross-crate.
+
 extern mod trait_superkinds_in_metadata;
-use trait_superkinds_in_metadata::{Foo, Bar};
+use trait_superkinds_in_metadata::{RequiresRequiresFreezeAndSend, RequiresFreeze};
 
 #[deriving(Eq)]
 struct X<T>(T);
 
-impl <T: Freeze> Bar for X<T> { }
-impl <T: Freeze+Send> Foo for X<T> { }
+impl <T: Freeze> RequiresFreeze for X<T> { }
+impl <T: Freeze+Send> RequiresRequiresFreezeAndSend for X<T> { }
 
-fn foo<T: Foo>(val: T, chan: std::comm::Chan<T>) {
+fn foo<T: RequiresRequiresFreezeAndSend>(val: T, chan: std::comm::Chan<T>) {
     chan.send(val);
 }
 
diff --git a/src/test/run-pass/builtin-superkinds-capabilities.rs b/src/test/run-pass/builtin-superkinds-capabilities.rs
index 639c78bd657..ebbb3d38694 100644
--- a/src/test/run-pass/builtin-superkinds-capabilities.rs
+++ b/src/test/run-pass/builtin-superkinds-capabilities.rs
@@ -8,6 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Tests "capabilities" granted by traits that inherit from super-
+// builtin-kinds, e.g., if a trait requires Send to implement, then
+// at usage site of that trait, we know we have the Send capability.
+
 trait Foo : Send { }
 
 impl <T: Send> Foo for T { }
diff --git a/src/test/run-pass/builtin-superkinds-in-metadata.rs b/src/test/run-pass/builtin-superkinds-in-metadata.rs
index fc445058c04..9f68976a4a4 100644
--- a/src/test/run-pass/builtin-superkinds-in-metadata.rs
+++ b/src/test/run-pass/builtin-superkinds-in-metadata.rs
@@ -10,13 +10,15 @@
 
 // aux-build:trait_superkinds_in_metadata.rs
 
+// Tests (correct) usage of trait super-builtin-kinds cross-crate.
+
 extern mod trait_superkinds_in_metadata;
-use trait_superkinds_in_metadata::{Foo, Bar};
+use trait_superkinds_in_metadata::{RequiresRequiresFreezeAndSend, RequiresFreeze};
 
 struct X<T>(T);
 
-impl <T:Freeze> Bar for X<T> { }
+impl <T:Freeze> RequiresFreeze for X<T> { }
 
-impl <T:Freeze+Send> Foo for X<T> { }
+impl <T:Freeze+Send> RequiresRequiresFreezeAndSend for X<T> { }
 
 fn main() { }
diff --git a/src/test/run-pass/builtin-superkinds-shadow-typaram.rs b/src/test/run-pass/builtin-superkinds-phantom-typaram.rs
similarity index 74%
rename from src/test/run-pass/builtin-superkinds-shadow-typaram.rs
rename to src/test/run-pass/builtin-superkinds-phantom-typaram.rs
index 193efb06d39..b6e58bfbf3d 100644
--- a/src/test/run-pass/builtin-superkinds-shadow-typaram.rs
+++ b/src/test/run-pass/builtin-superkinds-phantom-typaram.rs
@@ -8,6 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Tests that even when a type paramenter doesn't implement a required
+// super-builtin-kind of a trait, if the type parameter is never used,
+// the type can implement the trait anyway.
+
 trait Foo : Send { }
 
 struct X<T>(());
diff --git a/src/test/run-pass/builtin-superkinds-simple.rs b/src/test/run-pass/builtin-superkinds-simple.rs
index 5ecac6a0f7a..61a22d97498 100644
--- a/src/test/run-pass/builtin-superkinds-simple.rs
+++ b/src/test/run-pass/builtin-superkinds-simple.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Simple test case of implementing a trait with super-builtin-kinds.
+
 trait Foo : Send { }
 
 impl Foo for int { }
diff --git a/src/test/run-pass/builtin-superkinds-typaram.rs b/src/test/run-pass/builtin-superkinds-typaram.rs
index eda04a780ee..7dfd1e0629f 100644
--- a/src/test/run-pass/builtin-superkinds-typaram.rs
+++ b/src/test/run-pass/builtin-superkinds-typaram.rs
@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Tests correct implementation of traits with super-builtin-kinds
+// using a bounded type parameter.
+
 trait Foo : Send { }
 
 impl <T: Send> Foo for T { }