diff --git a/.gitignore b/.gitignore
index 9611428d..fbbf5d70 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-**/dockcross-linux-aarch64
\ No newline at end of file
+**/dockcross-linux-aarch64
diff --git a/01_bareminimum/Xargo.toml b/01_bareminimum/Xargo.toml
new file mode 100644
index 00000000..d0d5706f
--- /dev/null
+++ b/01_bareminimum/Xargo.toml
@@ -0,0 +1,5 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+stage = 1
diff --git a/02_multicore_rust/Xargo.toml b/02_multicore_rust/Xargo.toml
new file mode 100644
index 00000000..d0d5706f
--- /dev/null
+++ b/02_multicore_rust/Xargo.toml
@@ -0,0 +1,5 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+stage = 1
diff --git a/03_uart1/Xargo.toml b/03_uart1/Xargo.toml
new file mode 100644
index 00000000..d0d5706f
--- /dev/null
+++ b/03_uart1/Xargo.toml
@@ -0,0 +1,5 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+stage = 1
diff --git a/04_mailboxes/Cargo.lock b/04_mailboxes/Cargo.lock
index 6423a007..3352bcb2 100644
--- a/04_mailboxes/Cargo.lock
+++ b/04_mailboxes/Cargo.lock
@@ -3,7 +3,6 @@ name = "kernel8"
 version = "0.1.0"
 dependencies = [
  "raspi3_glue 0.1.0",
- "rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -11,11 +10,6 @@ dependencies = [
 name = "raspi3_glue"
 version = "0.1.0"
 
-[[package]]
-name = "rlibc"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "vcell"
 version = "0.1.0"
@@ -30,6 +24,5 @@ dependencies = [
 ]
 
 [metadata]
-"checksum rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc874b127765f014d792f16763a81245ab80500e2ad921ed4ee9e82481ee08fe"
 "checksum vcell 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "45c297f0afb6928cd08ab1ff9d95e99392595ea25ae1b5ecf822ff8764e57a0d"
 "checksum volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0d67cb4616d99b940db1d6bd28844ff97108b498a6ca850e5b6191a532063286"
diff --git a/04_mailboxes/Cargo.toml b/04_mailboxes/Cargo.toml
index 8e79f96f..df9e43a9 100644
--- a/04_mailboxes/Cargo.toml
+++ b/04_mailboxes/Cargo.toml
@@ -6,4 +6,3 @@ authors = ["Andre Richter <andre.o.richter@gmail.com>"]
 [dependencies]
 raspi3_glue = { path = "raspi3_glue" }
 volatile-register = "0.2.0"
-rlibc = "1.0"
diff --git a/04_mailboxes/README.md b/04_mailboxes/README.md
index df509f27..9b28a564 100644
--- a/04_mailboxes/README.md
+++ b/04_mailboxes/README.md
@@ -35,17 +35,15 @@ Where each tag looks like:
  n+3. optional value buffer
 ```
 
-### rlibc
+### Xargo.toml
 
 The mailbox buffer is a fixed array that is zero-initialized. To achieve
 zero-initialization, Rust utilizies and links to the `memset()` function, which
 is normally provided by `libc`.
 
 Since we are writing a `no_std` crate, we need to explicitly provide it. The
-easiest way is pulling in [rlibc] by adding it as an `extern crate` to `main.rs`
-and adding the dependency to `Cargo.toml`.
-
-[rlibc]: https://github.com/alexcrichton/rlibc
+easiest way is pulling in the `mem` feature of the `compiler_builtins` by adding
+it to `Xargo.toml`.
 
 ### Synchronization
 
diff --git a/04_mailboxes/Xargo.toml b/04_mailboxes/Xargo.toml
new file mode 100644
index 00000000..163024ec
--- /dev/null
+++ b/04_mailboxes/Xargo.toml
@@ -0,0 +1,6 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+features = ["mem"] # for memset() et al.
+stage = 1
diff --git a/04_mailboxes/kernel8.img b/04_mailboxes/kernel8.img
index 4f18a092..f36cf015 100755
Binary files a/04_mailboxes/kernel8.img and b/04_mailboxes/kernel8.img differ
diff --git a/04_mailboxes/src/main.rs b/04_mailboxes/src/main.rs
index ed6ac757..5fa2e798 100644
--- a/04_mailboxes/src/main.rs
+++ b/04_mailboxes/src/main.rs
@@ -26,7 +26,6 @@
 #![feature(asm)]
 
 extern crate raspi3_glue;
-extern crate rlibc; // for memset et al.b
 extern crate volatile_register;
 
 const MMIO_BASE: u32 = 0x3F00_0000;
diff --git a/05_uart0/Cargo.lock b/05_uart0/Cargo.lock
index 6423a007..3352bcb2 100644
--- a/05_uart0/Cargo.lock
+++ b/05_uart0/Cargo.lock
@@ -3,7 +3,6 @@ name = "kernel8"
 version = "0.1.0"
 dependencies = [
  "raspi3_glue 0.1.0",
- "rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -11,11 +10,6 @@ dependencies = [
 name = "raspi3_glue"
 version = "0.1.0"
 
-[[package]]
-name = "rlibc"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "vcell"
 version = "0.1.0"
@@ -30,6 +24,5 @@ dependencies = [
 ]
 
 [metadata]
-"checksum rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc874b127765f014d792f16763a81245ab80500e2ad921ed4ee9e82481ee08fe"
 "checksum vcell 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "45c297f0afb6928cd08ab1ff9d95e99392595ea25ae1b5ecf822ff8764e57a0d"
 "checksum volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0d67cb4616d99b940db1d6bd28844ff97108b498a6ca850e5b6191a532063286"
diff --git a/05_uart0/Cargo.toml b/05_uart0/Cargo.toml
index 8e79f96f..df9e43a9 100644
--- a/05_uart0/Cargo.toml
+++ b/05_uart0/Cargo.toml
@@ -6,4 +6,3 @@ authors = ["Andre Richter <andre.o.richter@gmail.com>"]
 [dependencies]
 raspi3_glue = { path = "raspi3_glue" }
 volatile-register = "0.2.0"
-rlibc = "1.0"
diff --git a/05_uart0/Xargo.toml b/05_uart0/Xargo.toml
new file mode 100644
index 00000000..163024ec
--- /dev/null
+++ b/05_uart0/Xargo.toml
@@ -0,0 +1,6 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+features = ["mem"] # for memset() et al.
+stage = 1
diff --git a/05_uart0/kernel8.img b/05_uart0/kernel8.img
index c37ec3fd..f2cc1a91 100755
Binary files a/05_uart0/kernel8.img and b/05_uart0/kernel8.img differ
diff --git a/05_uart0/src/main.rs b/05_uart0/src/main.rs
index 5d1b9351..cd0ad5c5 100644
--- a/05_uart0/src/main.rs
+++ b/05_uart0/src/main.rs
@@ -26,7 +26,6 @@
 #![feature(asm)]
 
 extern crate raspi3_glue;
-extern crate rlibc; // for memset et al.b
 extern crate volatile_register;
 
 const MMIO_BASE: u32 = 0x3F00_0000;
diff --git a/06_random/Cargo.lock b/06_random/Cargo.lock
index 6423a007..3352bcb2 100644
--- a/06_random/Cargo.lock
+++ b/06_random/Cargo.lock
@@ -3,7 +3,6 @@ name = "kernel8"
 version = "0.1.0"
 dependencies = [
  "raspi3_glue 0.1.0",
- "rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -11,11 +10,6 @@ dependencies = [
 name = "raspi3_glue"
 version = "0.1.0"
 
-[[package]]
-name = "rlibc"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "vcell"
 version = "0.1.0"
@@ -30,6 +24,5 @@ dependencies = [
 ]
 
 [metadata]
-"checksum rlibc 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc874b127765f014d792f16763a81245ab80500e2ad921ed4ee9e82481ee08fe"
 "checksum vcell 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "45c297f0afb6928cd08ab1ff9d95e99392595ea25ae1b5ecf822ff8764e57a0d"
 "checksum volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0d67cb4616d99b940db1d6bd28844ff97108b498a6ca850e5b6191a532063286"
diff --git a/06_random/Cargo.toml b/06_random/Cargo.toml
index 8e79f96f..df9e43a9 100644
--- a/06_random/Cargo.toml
+++ b/06_random/Cargo.toml
@@ -6,4 +6,3 @@ authors = ["Andre Richter <andre.o.richter@gmail.com>"]
 [dependencies]
 raspi3_glue = { path = "raspi3_glue" }
 volatile-register = "0.2.0"
-rlibc = "1.0"
diff --git a/06_random/Xargo.toml b/06_random/Xargo.toml
new file mode 100644
index 00000000..163024ec
--- /dev/null
+++ b/06_random/Xargo.toml
@@ -0,0 +1,6 @@
+[dependencies.core]
+stage = 0
+
+[dependencies.compiler_builtins]
+features = ["mem"] # for memset() et al.
+stage = 1
diff --git a/06_random/kernel8.img b/06_random/kernel8.img
index 7c8e4fe5..f5627ac4 100755
Binary files a/06_random/kernel8.img and b/06_random/kernel8.img differ
diff --git a/06_random/src/main.rs b/06_random/src/main.rs
index 248ee603..f039b4d5 100644
--- a/06_random/src/main.rs
+++ b/06_random/src/main.rs
@@ -26,7 +26,6 @@
 #![feature(asm)]
 
 extern crate raspi3_glue;
-extern crate rlibc; // for memset et al.b
 extern crate volatile_register;
 
 const MMIO_BASE: u32 = 0x3F00_0000;