diff --git a/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs b/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
index c284840ecb4bd..2436c7ddbf6ad 100644
--- a/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
+++ b/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
@@ -15,7 +15,7 @@ pub fn target() -> TargetResult {
         llvm_target: "mips64-unknown-linux-gnuabi64".to_string(),
         target_endian: "big".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
+        data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs b/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
index 17895836fe87b..c58e9b04a6386 100644
--- a/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
+++ b/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
@@ -15,7 +15,7 @@ pub fn target() -> TargetResult {
         llvm_target: "mips64el-unknown-linux-gnuabi64".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
+        data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
index 909c5488dcb70..ad28b899fbb6e 100644
--- a/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
@@ -23,7 +23,7 @@ pub fn target() -> TargetResult {
         llvm_target: "powerpc64-unknown-linux-gnu".to_string(),
         target_endian: "big".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "E-m:e-i64:64-n32:64".to_string(),
+        data_layout: "E-m:e-i64:64-i128:128-n32:64".to_string(),
         arch: "powerpc64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
index a692346ca0ffe..3354fc04ecf95 100644
--- a/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
@@ -23,7 +23,7 @@ pub fn target() -> TargetResult {
         llvm_target: "powerpc64le-unknown-linux-gnu".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-n32:64".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-n32:64".to_string(),
         arch: "powerpc64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/s390x_unknown_linux_gnu.rs b/src/librustc_back/target/s390x_unknown_linux_gnu.rs
index 6e2dd6cd67c93..1dc3ca61a513f 100644
--- a/src/librustc_back/target/s390x_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/s390x_unknown_linux_gnu.rs
@@ -24,7 +24,7 @@ pub fn target() -> TargetResult {
         llvm_target: "s390x-unknown-linux-gnu".to_string(),
         target_endian: "big".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-a:8:16-n32:64".to_string(),
+        data_layout: "E-m:e-i1:8:16-i8:8:16-i64:64-i128:128-f128:64-a:8:16-n32:64".to_string(),
         arch: "s390x".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/sparc64_unknown_linux_gnu.rs b/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
index f627cc18f0b3d..55a269a5a5714 100644
--- a/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "sparc64-unknown-linux-gnu".to_string(),
         target_endian: "big".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "E-m:e-i64:64-n32:64-S128".to_string(),
+        data_layout: "E-m:e-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "sparc64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/sparc64_unknown_netbsd.rs b/src/librustc_back/target/sparc64_unknown_netbsd.rs
index f30cebbc2d5a7..80f9a9785bd89 100644
--- a/src/librustc_back/target/sparc64_unknown_netbsd.rs
+++ b/src/librustc_back/target/sparc64_unknown_netbsd.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "sparc64-unknown-netbsd".to_string(),
         target_endian: "big".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "E-m:e-i64:64-n32:64-S128".to_string(),
+        data_layout: "E-m:e-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "sparc64".to_string(),
         target_os: "netbsd".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_apple_darwin.rs b/src/librustc_back/target/x86_64_apple_darwin.rs
index b3c1561dbcc0b..7f8c5bcda0f9a 100644
--- a/src/librustc_back/target/x86_64_apple_darwin.rs
+++ b/src/librustc_back/target/x86_64_apple_darwin.rs
@@ -21,7 +21,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-apple-darwin".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:o-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:o-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "macos".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_apple_ios.rs b/src/librustc_back/target/x86_64_apple_ios.rs
index 7a58bb34ce7f6..6c13c483751f0 100644
--- a/src/librustc_back/target/x86_64_apple_ios.rs
+++ b/src/librustc_back/target/x86_64_apple_ios.rs
@@ -17,7 +17,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-apple-ios".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:o-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:o-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_pc_windows_gnu.rs b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
index 321585cd65eb3..da0ca3011cc80 100644
--- a/src/librustc_back/target/x86_64_pc_windows_gnu.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-pc-windows-gnu".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:w-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:w-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/x86_64_pc_windows_msvc.rs b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
index ea8909d213e80..15e5af0739d87 100644
--- a/src/librustc_back/target/x86_64_pc_windows_msvc.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
@@ -19,7 +19,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-pc-windows-msvc".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:w-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:w-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
diff --git a/src/librustc_back/target/x86_64_rumprun_netbsd.rs b/src/librustc_back/target/x86_64_rumprun_netbsd.rs
index 3313721439696..f8e28a2bfe16a 100644
--- a/src/librustc_back/target/x86_64_rumprun_netbsd.rs
+++ b/src/librustc_back/target/x86_64_rumprun_netbsd.rs
@@ -29,7 +29,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-rumprun-netbsd".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "netbsd".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_sun_solaris.rs b/src/librustc_back/target/x86_64_sun_solaris.rs
index 8e4fd94e7bce4..84bd7d175e00c 100644
--- a/src/librustc_back/target/x86_64_sun_solaris.rs
+++ b/src/librustc_back/target/x86_64_sun_solaris.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-pc-solaris".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "solaris".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_bitrig.rs b/src/librustc_back/target/x86_64_unknown_bitrig.rs
index eda16c29466b5..c0af8c6c43658 100644
--- a/src/librustc_back/target/x86_64_unknown_bitrig.rs
+++ b/src/librustc_back/target/x86_64_unknown_bitrig.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-bitrig".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "bitrig".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_dragonfly.rs b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
index 194efb8fc2322..b5ad9de1eb776 100644
--- a/src/librustc_back/target/x86_64_unknown_dragonfly.rs
+++ b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-dragonfly".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "dragonfly".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_freebsd.rs b/src/librustc_back/target/x86_64_unknown_freebsd.rs
index b127bee163b86..cb621f4d2a48e 100644
--- a/src/librustc_back/target/x86_64_unknown_freebsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_freebsd.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-freebsd".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "freebsd".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_fuchsia.rs b/src/librustc_back/target/x86_64_unknown_fuchsia.rs
index 08fe17a556ecc..b32d7e5035d67 100644
--- a/src/librustc_back/target/x86_64_unknown_fuchsia.rs
+++ b/src/librustc_back/target/x86_64_unknown_fuchsia.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-fuchsia".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "fuchsia".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_haiku.rs b/src/librustc_back/target/x86_64_unknown_haiku.rs
index 7cf0599037c1e..9bf0434cad7e4 100644
--- a/src/librustc_back/target/x86_64_unknown_haiku.rs
+++ b/src/librustc_back/target/x86_64_unknown_haiku.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-haiku".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "haiku".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
index f95bcb556e57f..294f07929a38f 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-linux-gnu".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_linux_musl.rs b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
index c3bf9dcca6ee4..2e88a9c05366d 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_musl.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-linux-musl".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "linux".to_string(),
         target_env: "musl".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_netbsd.rs b/src/librustc_back/target/x86_64_unknown_netbsd.rs
index 87a7c184644d5..e8781c210d663 100644
--- a/src/librustc_back/target/x86_64_unknown_netbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_netbsd.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-netbsd".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "netbsd".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_openbsd.rs b/src/librustc_back/target/x86_64_unknown_openbsd.rs
index e9d645b0d38f2..ceaad21661ad1 100644
--- a/src/librustc_back/target/x86_64_unknown_openbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_openbsd.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-openbsd".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "openbsd".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_back/target/x86_64_unknown_redox.rs b/src/librustc_back/target/x86_64_unknown_redox.rs
index cecac06b23527..fcfd698a96e43 100644
--- a/src/librustc_back/target/x86_64_unknown_redox.rs
+++ b/src/librustc_back/target/x86_64_unknown_redox.rs
@@ -20,7 +20,7 @@ pub fn target() -> TargetResult {
         llvm_target: "x86_64-unknown-redox".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
-        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        data_layout: "e-m:e-i64:64-i128:128-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
         target_os: "redox".to_string(),
         target_env: "".to_string(),
diff --git a/src/librustc_llvm/ffi.rs b/src/librustc_llvm/ffi.rs
index 6815da4cc20fd..46d0469ba47a2 100644
--- a/src/librustc_llvm/ffi.rs
+++ b/src/librustc_llvm/ffi.rs
@@ -691,6 +691,7 @@ extern "C" {
                                        -> ValueRef;
     pub fn LLVMSetFunctionCallConv(Fn: ValueRef, CC: c_uint);
     pub fn LLVMRustAddDereferenceableAttr(Fn: ValueRef, index: c_uint, bytes: u64);
+    pub fn LLVMRustAddAlignAttr(Fn: ValueRef, index: c_uint, bytes: u64);
     pub fn LLVMRustAddFunctionAttribute(Fn: ValueRef, index: c_uint, attr: Attribute);
     pub fn LLVMRustAddFunctionAttrStringValue(Fn: ValueRef,
                                               index: c_uint,
@@ -721,6 +722,7 @@ extern "C" {
     pub fn LLVMSetInstructionCallConv(Instr: ValueRef, CC: c_uint);
     pub fn LLVMRustAddCallSiteAttribute(Instr: ValueRef, index: c_uint, attr: Attribute);
     pub fn LLVMRustAddDereferenceableCallSiteAttr(Instr: ValueRef, index: c_uint, bytes: u64);
+    pub fn LLVMRustAddAlignCallSiteAttr(Instr: ValueRef, index: c_uint, bytes: u64);
 
     // Operations on load/store instructions (only)
     pub fn LLVMSetVolatile(MemoryAccessInst: ValueRef, volatile: Bool);
diff --git a/src/librustc_trans/abi.rs b/src/librustc_trans/abi.rs
index ad4bb0fce22ad..fb792a2beb850 100644
--- a/src/librustc_trans/abi.rs
+++ b/src/librustc_trans/abi.rs
@@ -96,6 +96,7 @@ impl ArgAttribute {
 pub struct ArgAttributes {
     regular: ArgAttribute,
     dereferenceable_bytes: u64,
+    align: u64,
 }
 
 impl ArgAttributes {
@@ -109,6 +110,11 @@ impl ArgAttributes {
         self
     }
 
+    pub fn set_align(&mut self, align: u64) -> &mut Self {
+        self.align = align;
+        self
+    }
+
     pub fn apply_llfn(&self, idx: AttributePlace, llfn: ValueRef) {
         unsafe {
             self.regular.for_each_kind(|attr| attr.apply_llfn(idx, llfn));
@@ -117,6 +123,9 @@ impl ArgAttributes {
                                                      idx.as_uint(),
                                                      self.dereferenceable_bytes);
             }
+            if self.align != 0 {
+                llvm::LLVMRustAddAlignAttr(llfn, idx.as_uint(), self.align);
+            }
         }
     }
 
@@ -128,6 +137,9 @@ impl ArgAttributes {
                                                              idx.as_uint(),
                                                              self.dereferenceable_bytes);
             }
+            if self.align != 0 {
+                llvm::LLVMRustAddAlignCallSiteAttr(callsite, idx.as_uint(), self.align);
+            }
         }
     }
 }
diff --git a/src/librustc_trans/cabi_asmjs.rs b/src/librustc_trans/cabi_asmjs.rs
index f410627400c34..465ffb8d3a22a 100644
--- a/src/librustc_trans/cabi_asmjs.rs
+++ b/src/librustc_trans/cabi_asmjs.rs
@@ -11,7 +11,7 @@
 #![allow(non_upper_case_globals)]
 
 use llvm::{Struct, Array};
-use abi::{FnType, ArgType, ArgAttribute};
+use abi::{FnType, ArgType, ArgAttribute, ty_align};
 use context::CrateContext;
 
 // Data layout: e-p:32:32-i64:64-v128:32:128-n32-S128
@@ -40,6 +40,7 @@ fn classify_arg_ty(ccx: &CrateContext, arg: &mut ArgType) {
     if arg.ty.is_aggregate() {
         arg.make_indirect(ccx);
         arg.attrs.set(ArgAttribute::ByVal);
+        arg.attrs.set_align(ty_align(arg.ty, 0) as u64);
     }
 }
 
diff --git a/src/librustc_trans/cabi_x86.rs b/src/librustc_trans/cabi_x86.rs
index fea005f3d77da..47ebdb8c2f1a8 100644
--- a/src/librustc_trans/cabi_x86.rs
+++ b/src/librustc_trans/cabi_x86.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 use llvm::*;
-use abi::{ArgAttribute, FnType};
+use abi::{ArgAttribute, FnType, ty_align};
 use type_::Type;
 use super::common::*;
 use super::machine::*;
@@ -53,6 +53,7 @@ pub fn compute_abi_info(ccx: &CrateContext, fty: &mut FnType, flavor: Flavor) {
         if arg.ty.kind() == Struct {
             arg.make_indirect(ccx);
             arg.attrs.set(ArgAttribute::ByVal);
+            arg.attrs.set_align(ty_align(arg.ty, 0) as u64);
         } else {
             arg.extend_integer_width_to(32);
         }
diff --git a/src/librustc_trans/cabi_x86_64.rs b/src/librustc_trans/cabi_x86_64.rs
index 7f2fdbf000b65..865aa18bcbdde 100644
--- a/src/librustc_trans/cabi_x86_64.rs
+++ b/src/librustc_trans/cabi_x86_64.rs
@@ -16,7 +16,7 @@ use self::RegClass::*;
 
 use llvm::{Integer, Pointer, Float, Double};
 use llvm::{Struct, Array, Vector};
-use abi::{self, ArgType, ArgAttribute, FnType};
+use abi::{self, ArgType, ArgAttribute, FnType, ty_align};
 use context::CrateContext;
 use type_::Type;
 
@@ -343,6 +343,7 @@ pub fn compute_abi_info(ccx: &CrateContext, fty: &mut FnType) {
                 arg.make_indirect(ccx);
                 if let Some(attr) = ind_attr {
                     arg.attrs.set(attr);
+                    arg.attrs.set_align(ty_align(arg.ty, 0) as u64);
                 }
             } else {
                 arg.cast = Some(llreg_ty(ccx, &cls));
diff --git a/src/librustc_trans/context.rs b/src/librustc_trans/context.rs
index 413b643740861..2c1eb91026838 100644
--- a/src/librustc_trans/context.rs
+++ b/src/librustc_trans/context.rs
@@ -374,8 +374,11 @@ unsafe fn create_context_and_module(sess: &Session, mod_name: &str) -> (ContextR
         // FIXME(#34960)
         let cfg_llvm_root = option_env!("CFG_LLVM_ROOT").unwrap_or("");
         let custom_llvm_used = cfg_llvm_root.trim() != "";
+        // Ignore any `-i128:128` that we add to our own data-layouts
+        let this_dl = sess.target.target.data_layout.replace("-i128:128", "");
+        let that_dl = data_layout.replace("-i128:128", "");
 
-        if !custom_llvm_used && sess.target.target.data_layout != data_layout {
+        if !custom_llvm_used && this_dl != that_dl {
             bug!("data-layout for builtin `{}` target, `{}`, \
                   differs from LLVM default, `{}`",
                  sess.target.target.llvm_target,
diff --git a/src/rt/rust_test_helpers.c b/src/rt/rust_test_helpers.c
index f2d9119a7d156..4e71f32bab338 100644
--- a/src/rt/rust_test_helpers.c
+++ b/src/rt/rust_test_helpers.c
@@ -269,10 +269,21 @@ LARGE_INTEGER increment_all_parts(LARGE_INTEGER li) {
     return li;
 }
 
-#define DO_INT128_TEST !(defined(WIN32) || defined(_WIN32) || defined(__WIN32)) && \
-    defined(__amd64__)
+#if !(defined(WIN32) || defined(_WIN32) || defined(__WIN32)) && defined(__amd64__)
 
-#if DO_INT128_TEST
+struct Foo {
+    __int128 a;
+    int8_t b;
+    uint16_t c;
+};
+
+struct Foo adt_id(struct Foo foo) {
+    return foo;
+}
+
+struct Foo adt_clone(struct Foo *foo) {
+    return *foo;
+}
 
 unsigned __int128 identity(unsigned __int128 a) {
     return a;
diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index ea31e8dab678f..593cc4972bd02 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -174,6 +174,17 @@ extern "C" void LLVMRustAddDereferenceableCallSiteAttr(LLVMValueRef Instr,
       AttributeSet::get(Call->getContext(), Index, B)));
 }
 
+extern "C" void LLVMRustAddAlignCallSiteAttr(LLVMValueRef Instr,
+                                             unsigned Index,
+                                             uint64_t Bytes) {
+  CallSite Call = CallSite(unwrap<Instruction>(Instr));
+  AttrBuilder B;
+  B.addAlignmentAttr(Bytes);
+  Call.setAttributes(Call.getAttributes().addAttributes(
+      Call->getContext(), Index,
+      AttributeSet::get(Call->getContext(), Index, B)));
+}
+
 extern "C" void LLVMRustAddFunctionAttribute(LLVMValueRef Fn, unsigned Index,
                                              LLVMRustAttribute RustAttr) {
   Function *A = unwrap<Function>(Fn);
@@ -190,6 +201,14 @@ extern "C" void LLVMRustAddDereferenceableAttr(LLVMValueRef Fn, unsigned Index,
   A->addAttributes(Index, AttributeSet::get(A->getContext(), Index, B));
 }
 
+extern "C" void LLVMRustAddAlignAttr(LLVMValueRef Fn, unsigned Index,
+                                               uint64_t Bytes) {
+  Function *A = unwrap<Function>(Fn);
+  AttrBuilder B;
+  B.addAlignmentAttr(Bytes);
+  A->addAttributes(Index, AttributeSet::get(A->getContext(), Index, B));
+}
+
 extern "C" void LLVMRustAddFunctionAttrStringValue(LLVMValueRef Fn,
                                                    unsigned Index,
                                                    const char *Name,
diff --git a/src/test/run-pass/i128-ffi.rs b/src/test/run-pass/i128-ffi.rs
index 3b5f4884d21e7..5a1335a59fbda 100644
--- a/src/test/run-pass/i128-ffi.rs
+++ b/src/test/run-pass/i128-ffi.rs
@@ -22,11 +22,21 @@
 
 #![feature(i128_type)]
 
+#[repr(C)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct Foo {
+    a: i128,
+    b: i8,
+    c: u16,
+}
+
 #[link(name = "rust_test_helpers", kind = "static")]
 extern "C" {
     fn identity(f: u128) -> u128;
     fn square(f: i128) -> i128;
     fn sub(f: i128, f: i128) -> i128;
+    fn adt_id(f: Foo) -> Foo;
+    fn adt_clone(f: *const Foo) -> Foo;
 }
 
 fn main() {
@@ -41,5 +51,10 @@ fn main() {
         let k_d = 0x2468_ACF1_3579_BDFF_DB97_530E_CA86_420;
         let k_out = sub(k_d, k);
         assert_eq!(k, k_out);
+        let a = Foo { a: 1, b: 2, c: 3 };
+        let b = adt_id(a);
+        assert_eq!(a, b);
+        let b = adt_clone(&a);
+        assert_eq!(a, b);
     }
 }