diff --git a/src/libcollections/hashmap.rs b/src/libcollections/hashmap.rs
index bd0e2ebec6f..9d08bf17668 100644
--- a/src/libcollections/hashmap.rs
+++ b/src/libcollections/hashmap.rs
@@ -1595,6 +1595,7 @@ pub type SetAlgebraItems<'a, T, H> =
 mod test_map {
     use super::HashMap;
     use std::cmp::Equiv;
+    use std::hash::Hash;
     use std::iter::{Iterator,range_inclusive,range_step_inclusive};
     use std::local_data;
     use std::vec;
@@ -1607,6 +1608,12 @@ mod test_map {
             this == *other
         }
     }
+    impl<S: Writer> Hash<S> for KindaIntLike {
+        fn hash(&self, state: &mut S) {
+            let KindaIntLike(this) = *self;
+            this.hash(state)
+        }
+    }
 
     #[test]
     fn test_create_capacity_zero() {
@@ -1848,11 +1855,12 @@ mod test_map {
     }
 
     #[test]
+    #[allow(experimental)]
     fn test_pop_equiv() {
         let mut m = HashMap::new();
         m.insert(1, 2);
-        assert_eq!(m.pop_equiv(&KindaIntLike(1), Some(2)));
-        assert_eq!(m.pop_equiv(&KindaIntLike(1), None));
+        assert_eq!(m.pop_equiv(&KindaIntLike(1)), Some(2));
+        assert_eq!(m.pop_equiv(&KindaIntLike(1)), None);
     }
 
     #[test]
diff --git a/src/libglob/lib.rs b/src/libglob/lib.rs
index e7661b26b76..3cad5bf8175 100644
--- a/src/libglob/lib.rs
+++ b/src/libglob/lib.rs
@@ -462,8 +462,8 @@ impl Pattern {
 fn fill_todo(todo: &mut Vec<(Path, uint)>, patterns: &[Pattern], idx: uint, path: &Path,
              options: MatchOptions) {
     // convert a pattern that's just many Char(_) to a string
-    fn pattern_as_str(pattern: &Pattern) -> Option<~str> {
-        let mut s = ~"";
+    fn pattern_as_str(pattern: &Pattern) -> Option<StrBuf> {
+        let mut s = StrBuf::new();
         for token in pattern.tokens.iter() {
             match *token {
                 Char(c) => s.push_char(c),
@@ -493,8 +493,8 @@ fn fill_todo(todo: &mut Vec<(Path, uint)>, patterns: &[Pattern], idx: uint, path
             // continue. So instead of passing control back to the iterator,
             // we can just check for that one entry and potentially recurse
             // right away.
-            let special = "." == s || ".." == s;
-            let next_path = path.join(s);
+            let special = "." == s.as_slice() || ".." == s.as_slice();
+            let next_path = path.join(s.as_slice());
             if (special && path.is_dir()) || (!special && next_path.exists()) {
                 add(todo, next_path);
             }
diff --git a/src/libnative/io/process.rs b/src/libnative/io/process.rs
index 8ef46239e61..e3bb938995b 100644
--- a/src/libnative/io/process.rs
+++ b/src/libnative/io/process.rs
@@ -402,7 +402,7 @@ fn make_command_line(prog: &str, args: &[~str]) -> ~str {
         cmd.push_char(' ');
         append_arg(&mut cmd, *arg);
     }
-    return cmd.to_owned_str();
+    return cmd.into_owned();
 
     fn append_arg(cmd: &mut StrBuf, arg: &str) {
         let quote = arg.chars().any(|c| c == ' ' || c == '\t');
diff --git a/src/libstd/hash/sip.rs b/src/libstd/hash/sip.rs
index 69b35df50e4..4a523e3d09e 100644
--- a/src/libstd/hash/sip.rs
+++ b/src/libstd/hash/sip.rs
@@ -291,7 +291,7 @@ mod tests {
     use iter::Iterator;
     use num::ToStrRadix;
     use option::{Some, None};
-    use str::{Str, OwnedStr};
+    use str::Str;
     use strbuf::StrBuf;
     use slice::{Vector, ImmutableVector, OwnedVector};
     use self::test::BenchHarness;
diff --git a/src/libstd/strbuf.rs b/src/libstd/strbuf.rs
index e9e50f0a07a..1fcc9c6465a 100644
--- a/src/libstd/strbuf.rs
+++ b/src/libstd/strbuf.rs
@@ -20,9 +20,11 @@ use iter::{Extendable, FromIterator, Iterator, range};
 use option::{None, Option, Some};
 use ptr::RawPtr;
 use slice::{OwnedVector, Vector};
+use str;
 use str::{OwnedStr, Str, StrSlice};
 use vec::Vec;
 
+/// A growable string stored as a UTF-8 encoded buffer.
 #[deriving(Clone, Eq, Ord, TotalEq, TotalOrd)]
 pub struct StrBuf {
     vec: Vec<u8>,
@@ -69,6 +71,23 @@ impl StrBuf {
         }
     }
 
+    /// Tries to create a new string buffer from the given byte
+    /// vector, validating that the vector is UTF-8 encoded.
+    #[inline]
+    pub fn from_utf8(vec: Vec<u8>) -> Option<StrBuf> {
+        if str::is_utf8(vec.as_slice()) {
+            Some(StrBuf { vec: vec })
+        } else {
+            None
+        }
+    }
+
+    /// Return the underlying byte buffer, encoded as UTF-8.
+    #[inline]
+    pub fn into_bytes(self) -> Vec<u8> {
+        self.vec
+    }
+
     /// Pushes the given string onto this buffer; then, returns `self` so that it can be used
     /// again.
     #[inline]
@@ -100,6 +119,7 @@ impl StrBuf {
         self.vec.push_all(string.as_bytes())
     }
 
+    /// Push `ch` onto the given string `count` times.
     #[inline]
     pub fn grow(&mut self, count: uint, ch: char) {
         for _ in range(0, count) {
@@ -352,4 +372,3 @@ mod tests {
         s.truncate(1);
     }
 }
-
diff --git a/src/test/bench/shootout-chameneos-redux.rs b/src/test/bench/shootout-chameneos-redux.rs
index 18900abace6..5ea84feffde 100644
--- a/src/test/bench/shootout-chameneos-redux.rs
+++ b/src/test/bench/shootout-chameneos-redux.rs
@@ -32,53 +32,62 @@ struct CreatureInfo {
     color: color
 }
 
-fn show_color(cc: color) -> ~str {
+fn show_color(cc: color) -> &'static str {
     match cc {
-        Red    => {~"red"}
-        Yellow => {~"yellow"}
-        Blue   => {~"blue"}
+        Red    => "red",
+        Yellow => "yellow",
+        Blue   => "blue"
     }
 }
 
-fn show_color_list(set: Vec<color>) -> ~str {
+fn show_color_list(set: Vec<color>) -> StrBuf {
     let mut out = StrBuf::new();
     for col in set.iter() {
         out.push_char(' ');
         out.push_str(show_color(*col));
     }
-    return out.to_owned_str();
+    out
 }
 
-fn show_digit(nn: uint) -> ~str {
+fn show_digit(nn: uint) -> &'static str {
     match nn {
-        0 => {~"zero"}
-        1 => {~"one"}
-        2 => {~"two"}
-        3 => {~"three"}
-        4 => {~"four"}
-        5 => {~"five"}
-        6 => {~"six"}
-        7 => {~"seven"}
-        8 => {~"eight"}
-        9 => {~"nine"}
+        0 => {"zero"}
+        1 => {"one"}
+        2 => {"two"}
+        3 => {"three"}
+        4 => {"four"}
+        5 => {"five"}
+        6 => {"six"}
+        7 => {"seven"}
+        8 => {"eight"}
+        9 => {"nine"}
         _ => {fail!("expected digits from 0 to 9...")}
     }
 }
 
-fn show_number(nn: uint) -> ~str {
-    let mut out = ~"";
+fn show_number(nn: uint) -> StrBuf {
+    let mut out = vec![];
     let mut num = nn;
     let mut dig;
-
-    if num == 0 { out = show_digit(0) };
+    let mut len = 0;
+    if num == 0 { out.push(show_digit(0)) };
 
     while num != 0 {
         dig = num % 10;
         num = num / 10;
-        out = show_digit(dig) + " " + out;
+        out.push(" ");
+        let s = show_digit(dig);
+        out.push(s);
+        len += 1 + s.len();
     }
+    len += 1;
+    out.push(" ");
 
-    return ~" " + out;
+    let mut ret = StrBuf::with_capacity(len);
+    for s in out.iter().rev() {
+        ret.push_str(*s);
+    }
+    ret
 }
 
 fn transform(aa: color, bb: color) -> color {
@@ -125,7 +134,7 @@ fn creature(
             option::None => {
                 // log creatures met and evil clones of self
                 let report = format!("{} {}",
-                                     creatures_met, show_number(evil_clones_met));
+                                     creatures_met, show_number(evil_clones_met).as_slice());
                 to_rendezvous_log.send(report);
                 break;
             }
diff --git a/src/test/bench/shootout-k-nucleotide-pipes.rs b/src/test/bench/shootout-k-nucleotide-pipes.rs
index ca88f107336..9dd76f5e475 100644
--- a/src/test/bench/shootout-k-nucleotide-pipes.rs
+++ b/src/test/bench/shootout-k-nucleotide-pipes.rs
@@ -15,17 +15,11 @@
 
 extern crate collections;
 
-use std::cmp::Ord;
-use std::comm;
 use collections::HashMap;
 use std::mem::replace;
 use std::option;
 use std::os;
-use std::io;
-use std::str;
 use std::strbuf::StrBuf;
-use std::task;
-use std::vec;
 
 fn f64_cmp(x: f64, y: f64) -> Ordering {
     // arbitrarily decide that NaNs are larger than everything.
@@ -66,16 +60,14 @@ fn sort_and_fmt(mm: &HashMap<Vec<u8> , uint>, total: uint) -> ~str {
 
    let mut buffer = StrBuf::new();
    for &(ref k, v) in pairs_sorted.iter() {
-       unsafe {
-           buffer.push_str(format!("{} {:0.3f}\n",
-                                   k.as_slice()
-                                    .to_ascii()
-                                    .to_upper()
-                                    .into_str(), v));
-       }
+       buffer.push_str(format!("{} {:0.3f}\n",
+                               k.as_slice()
+                               .to_ascii()
+                               .to_upper()
+                               .into_str(), v));
    }
 
-   return buffer.to_owned_str();
+   return buffer.into_owned();
 }
 
 // given a map, search for the frequency of a pattern
diff --git a/src/test/bench/shootout-k-nucleotide.rs b/src/test/bench/shootout-k-nucleotide.rs
index c9794d54829..a1daf45cea9 100644
--- a/src/test/bench/shootout-k-nucleotide.rs
+++ b/src/test/bench/shootout-k-nucleotide.rs
@@ -11,8 +11,6 @@
 // ignore-android see #10393 #13206
 // ignore-pretty
 
-use std::ascii::OwnedStrAsciiExt;
-use std::str;
 use std::strbuf::StrBuf;
 use std::slice;
 
@@ -50,8 +48,7 @@ impl Code {
         string.bytes().fold(Code(0u64), |a, b| a.push_char(b))
     }
 
-    // FIXME: Inefficient.
-    fn unpack(&self, frame: uint) -> ~str {
+    fn unpack(&self, frame: uint) -> StrBuf {
         let mut key = self.hash();
         let mut result = Vec::new();
         for _ in range(0, frame) {
@@ -60,7 +57,7 @@ impl Code {
         }
 
         result.reverse();
-        str::from_utf8_owned(result.move_iter().collect()).unwrap()
+        StrBuf::from_utf8(result).unwrap()
     }
 }
 
@@ -239,7 +236,7 @@ fn print_frequencies(frequencies: &Table, frame: uint) {
 
     for &(count, key) in vector.iter().rev() {
         println!("{} {:.3f}",
-                 key.unpack(frame),
+                 key.unpack(frame).as_slice(),
                  (count as f32 * 100.0) / (total_count as f32));
     }
     println!("");
@@ -249,14 +246,17 @@ fn print_occurrences(frequencies: &mut Table, occurrence: &'static str) {
     frequencies.lookup(Code::pack(occurrence), PrintCallback(occurrence))
 }
 
-fn get_sequence<R: Buffer>(r: &mut R, key: &str) -> ~[u8] {
-    let mut res = StrBuf::new();
+fn get_sequence<R: Buffer>(r: &mut R, key: &str) -> Vec<u8> {
+    let mut res = Vec::new();
     for l in r.lines().map(|l| l.ok().unwrap())
         .skip_while(|l| key != l.slice_to(key.len())).skip(1)
     {
-        res.push_str(l.trim());
+        res.push_all(l.trim().as_bytes());
     }
-    res.to_owned_str().into_ascii_upper().into_bytes()
+    for b in res.mut_iter() {
+        *b = b.to_ascii().to_upper().to_byte();
+    }
+    res
 }
 
 fn main() {
@@ -268,17 +268,17 @@ fn main() {
     };
 
     let mut frequencies = Table::new();
-    generate_frequencies(&mut frequencies, input, 1);
+    generate_frequencies(&mut frequencies, input.as_slice(), 1);
     print_frequencies(&frequencies, 1);
 
     frequencies = Table::new();
-    generate_frequencies(&mut frequencies, input, 2);
+    generate_frequencies(&mut frequencies, input.as_slice(), 2);
     print_frequencies(&frequencies, 2);
 
     for occurrence in OCCURRENCES.iter() {
         frequencies = Table::new();
         generate_frequencies(&mut frequencies,
-                             input,
+                             input.as_slice(),
                              occurrence.len());
         print_occurrences(&mut frequencies, *occurrence);
     }