diff --git a/mk/main.mk b/mk/main.mk
index fe333dae08ac7..e77182ae39993 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -18,7 +18,7 @@ CFG_RELEASE_NUM=1.15.0
 # An optional number to put after the label, e.g. '.2' -> '-beta.2'
 # NB Make sure it starts with a dot to conform to semver pre-release
 # versions (section 9)
-CFG_PRERELEASE_VERSION=.4
+CFG_PRERELEASE_VERSION=.5
 
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
diff --git a/src/bootstrap/check.rs b/src/bootstrap/check.rs
index 712c4c52baa5f..aa15825d8293c 100644
--- a/src/bootstrap/check.rs
+++ b/src/bootstrap/check.rs
@@ -13,6 +13,8 @@
 //! This file implements the various regression test suites that we execute on
 //! our CI.
 
+extern crate build_helper;
+
 use std::collections::HashSet;
 use std::env;
 use std::fmt;
@@ -543,7 +545,7 @@ pub fn distcheck(build: &Build) {
     build.run(&mut cmd);
     build.run(Command::new("./configure")
                      .current_dir(&dir));
-    build.run(Command::new("make")
+    build.run(Command::new(build_helper::make(&build.config.build))
                      .arg("check")
                      .current_dir(&dir));
 }
diff --git a/src/build_helper/lib.rs b/src/build_helper/lib.rs
index 07f9c91d3c787..d0d588f46a754 100644
--- a/src/build_helper/lib.rs
+++ b/src/build_helper/lib.rs
@@ -47,6 +47,8 @@ pub fn cc2ar(cc: &Path, target: &str) -> Option<PathBuf> {
         None
     } else if target.contains("musl") {
         Some(PathBuf::from("ar"))
+    } else if target.contains("openbsd") {
+        Some(PathBuf::from("ar"))
     } else {
         let parent = cc.parent().unwrap();
         let file = cc.file_name().unwrap().to_str().unwrap();
@@ -61,6 +63,16 @@ pub fn cc2ar(cc: &Path, target: &str) -> Option<PathBuf> {
     }
 }
 
+pub fn make(host: &str) -> PathBuf {
+    if host.contains("bitrig") || host.contains("dragonfly") ||
+        host.contains("freebsd") || host.contains("netbsd") ||
+        host.contains("openbsd") {
+        PathBuf::from("gmake")
+    } else {
+        PathBuf::from("make")
+    }
+}
+
 pub fn output(cmd: &mut Command) -> String {
     let output = match cmd.stderr(Stdio::inherit()).output() {
         Ok(status) => status,
diff --git a/src/liballoc_jemalloc/build.rs b/src/liballoc_jemalloc/build.rs
index fc849e7a50cc4..60b7875a97c84 100644
--- a/src/liballoc_jemalloc/build.rs
+++ b/src/liballoc_jemalloc/build.rs
@@ -151,7 +151,7 @@ fn main() {
     cmd.arg(format!("--build={}", build_helper::gnu_target(&host)));
 
     run(&mut cmd);
-    let mut make = Command::new("make");
+    let mut make = Command::new(build_helper::make(&host));
     make.current_dir(&build_dir)
         .arg("build_lib_static");
 
diff --git a/src/librustc_llvm/build.rs b/src/librustc_llvm/build.rs
index 50bc3e7b6243f..86c40a0208ad3 100644
--- a/src/librustc_llvm/build.rs
+++ b/src/librustc_llvm/build.rs
@@ -230,6 +230,13 @@ fn main() {
         }
     }
 
+    // OpenBSD has a particular C++ runtime library name
+    let stdcppname = if target.contains("openbsd") {
+        "estdc++"
+    } else {
+        "stdc++"
+    };
+
     // C++ runtime library
     if !target.contains("msvc") {
         if let Some(s) = env::var_os("LLVM_STATIC_STDCPP") {
@@ -237,11 +244,11 @@ fn main() {
             let path = PathBuf::from(s);
             println!("cargo:rustc-link-search=native={}",
                      path.parent().unwrap().display());
-            println!("cargo:rustc-link-lib=static=stdc++");
+            println!("cargo:rustc-link-lib=static={}", stdcppname);
         } else if cxxflags.contains("stdlib=libc++") {
             println!("cargo:rustc-link-lib=c++");
         } else {
-            println!("cargo:rustc-link-lib=stdc++");
+            println!("cargo:rustc-link-lib={}", stdcppname);
         }
     }
 }
diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 1087d1f24471b..b3eba50831698 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -104,7 +104,7 @@ fn build_libbacktrace(host: &str, target: &str) {
                 .env("AR", &ar)
                 .env("RANLIB", format!("{} s", ar.display()))
                 .env("CFLAGS", cflags));
-    run(Command::new("make")
+    run(Command::new(build_helper::make(host))
                 .current_dir(&build_dir)
                 .arg(format!("INCDIR={}", src_dir.display()))
                 .arg("-j").arg(env::var("NUM_JOBS").expect("NUM_JOBS was not set")));
diff --git a/src/test/run-pass/backtrace.rs b/src/test/run-pass/backtrace.rs
index c438c17f51e3a..75c665b04a123 100644
--- a/src/test/run-pass/backtrace.rs
+++ b/src/test/run-pass/backtrace.rs
@@ -10,6 +10,7 @@
 
 // ignore-android FIXME #17520
 // ignore-emscripten spawning processes is not supported
+// ignore-openbsd no support for libbacktrace without filename
 // compile-flags:-g
 
 use std::env;
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 3cc14541fcdf2..94461cd8e07af 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2108,7 +2108,16 @@ actual:\n\
         }
         self.create_dir_racy(&tmpdir);
 
-        let mut cmd = Command::new("make");
+        let host = &self.config.host;
+        let make = if host.contains("bitrig") || host.contains("dragonfly") ||
+            host.contains("freebsd") || host.contains("netbsd") ||
+            host.contains("openbsd") {
+            "gmake"
+        } else {
+            "make"
+        };
+
+        let mut cmd = Command::new(make);
         cmd.current_dir(&self.testpaths.file)
            .env("TARGET", &self.config.target)
            .env("PYTHON", &self.config.docck_python)