diff --git a/README.md b/README.md
index 6f184e25218..00bb501941d 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ or reading the [rustc dev guide][rustcguidebuild].
 1. Make sure you have installed the dependencies:
 
    * `g++` 5.1 or later or `clang++` 3.5 or later
-   * `python` 2.7 (but not 3.x)
+   * `python` 3 or 2.7
    * GNU `make` 3.81 or later
    * `cmake` 3.4.3 or later
    * `curl`
@@ -113,7 +113,7 @@ build.
                make \
                diffutils \
                tar \
-               mingw-w64-x86_64-python2 \
+               mingw-w64-x86_64-python \
                mingw-w64-x86_64-cmake \
                mingw-w64-x86_64-gcc
    ```
diff --git a/config.toml.example b/config.toml.example
index ce21b63467f..d4a77bb2960 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -168,11 +168,9 @@
 
 # Python interpreter to use for various tasks throughout the build, notably
 # rustdoc tests, the lldb python interpreter, and some dist bits and pieces.
-# Note that Python 2 is currently required.
 #
-# Defaults to python2.7, then python2. If neither executable can be found, then
-# it defaults to the Python interpreter used to execute x.py.
-#python = "python2.7"
+# Defaults to the Python interpreter used to execute x.py.
+#python = "python"
 
 # Force Cargo to check that Cargo.lock describes the precise dependency
 # set that all the Cargo.toml files create, instead of updating it.
diff --git a/configure b/configure
index eeb8d081d34..81e2001e4a5 100755
--- a/configure
+++ b/configure
@@ -11,6 +11,7 @@ try() {
     fi
 }
 
+try python3 "$@"
 try python2.7 "$@"
 try python27 "$@"
 try python2 "$@"
diff --git a/src/bootstrap/job.rs b/src/bootstrap/job.rs
index efeb86540b7..2fe9b06e426 100644
--- a/src/bootstrap/job.rs
+++ b/src/bootstrap/job.rs
@@ -103,7 +103,12 @@ pub unsafe fn setup(build: &mut Build) {
     };
 
     let parent = OpenProcess(PROCESS_DUP_HANDLE, FALSE, pid.parse().unwrap());
-    assert!(!parent.is_null(), "{}", io::Error::last_os_error());
+    assert!(
+        !parent.is_null(),
+        "PID `{}` doesn't seem to exist: {}",
+        pid,
+        io::Error::last_os_error()
+    );
     let mut parent_handle = ptr::null_mut();
     let r = DuplicateHandle(
         GetCurrentProcess(),
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 530e74da8ca..1760d655b3b 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -132,8 +132,6 @@ pub fn check(build: &mut Build) {
         .python
         .take()
         .map(|p| cmd_finder.must_have(p))
-        .or_else(|| cmd_finder.maybe_have("python2.7"))
-        .or_else(|| cmd_finder.maybe_have("python2"))
         .or_else(|| env::var_os("BOOTSTRAP_PYTHON").map(PathBuf::from)) // set by bootstrap.py
         .or_else(|| Some(cmd_finder.must_have("python")));
 
diff --git a/src/ci/docker/arm-android/Dockerfile b/src/ci/docker/arm-android/Dockerfile
index b934d1ce971..77514848167 100644
--- a/src/ci/docker/arm-android/Dockerfile
+++ b/src/ci/docker/arm-android/Dockerfile
@@ -31,7 +31,7 @@ ENV TARGETS=arm-linux-androideabi
 
 ENV RUST_CONFIGURE_ARGS --arm-linux-androideabi-ndk=/android/ndk/arm-14
 
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS
+ENV SCRIPT python3 ../x.py test --target $TARGETS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/armhf-gnu/Dockerfile b/src/ci/docker/armhf-gnu/Dockerfile
index 5373612279b..d1bc70689e1 100644
--- a/src/ci/docker/armhf-gnu/Dockerfile
+++ b/src/ci/docker/armhf-gnu/Dockerfile
@@ -14,7 +14,7 @@ RUN apt-get update -y && apt-get install -y --no-install-recommends \
       libc6-dev \
       libc6-dev-armhf-cross \
       make \
-      python2.7 \
+      python3 \
       qemu-system-arm \
       xz-utils
 
@@ -78,6 +78,6 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --qemu-armhf-rootfs=/tmp/rootfs
-ENV SCRIPT python2.7 ../x.py test --target arm-unknown-linux-gnueabihf
+ENV SCRIPT python3 ../x.py test --target arm-unknown-linux-gnueabihf
 
 ENV NO_CHANGE_USER=1
diff --git a/src/ci/docker/disabled/aarch64-gnu/Dockerfile b/src/ci/docker/disabled/aarch64-gnu/Dockerfile
index b2a3ba3ec26..9dd0435ac4f 100644
--- a/src/ci/docker/disabled/aarch64-gnu/Dockerfile
+++ b/src/ci/docker/disabled/aarch64-gnu/Dockerfile
@@ -14,7 +14,7 @@ RUN apt-get update -y && apt-get install -y --no-install-recommends \
       libc6-dev \
       libc6-dev-arm64-cross \
       make \
-      python2.7 \
+      python3 \
       qemu-system-aarch64 \
       xz-utils
 
@@ -75,5 +75,5 @@ RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS \
       --qemu-aarch64-rootfs=/tmp/rootfs
-ENV SCRIPT python2.7 ../x.py test --target aarch64-unknown-linux-gnu
+ENV SCRIPT python3 ../x.py test --target aarch64-unknown-linux-gnu
 ENV NO_CHANGE_USER=1
diff --git a/src/ci/docker/disabled/asmjs/Dockerfile b/src/ci/docker/disabled/asmjs/Dockerfile
index e27a2a529a8..3fa65511e94 100644
--- a/src/ci/docker/disabled/asmjs/Dockerfile
+++ b/src/ci/docker/disabled/asmjs/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -33,7 +33,7 @@ ENV EMCC_CFLAGS=-O1
 # Emscripten installation is user-specific
 ENV NO_CHANGE_USER=1
 
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS
+ENV SCRIPT python3 ../x.py test --target $TARGETS
 
 # This is almost identical to the wasm32-unknown-emscripten target, so
 # running with assertions again is not useful
diff --git a/src/ci/docker/disabled/dist-aarch64-android/Dockerfile b/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
index a7903b6f425..dea445c295c 100644
--- a/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
@@ -19,7 +19,7 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-cargo-openssl-static
 
-ENV SCRIPT python2.7 ../x.py dist --target $HOSTS --host $HOSTS
+ENV SCRIPT python3 ../x.py dist --target $HOSTS --host $HOSTS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-armv7-android/Dockerfile b/src/ci/docker/disabled/dist-armv7-android/Dockerfile
index c02a5e5a095..7227c41ccca 100644
--- a/src/ci/docker/disabled/dist-armv7-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-armv7-android/Dockerfile
@@ -33,11 +33,11 @@ ENV RUST_CONFIGURE_ARGS \
 # build to finish we use --warn-unresolved-symbols. Note that the missing
 # symbols does not affect std, only the compiler (llvm) and cargo (openssl).
 ENV SCRIPT \
-  python2.7 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
+  python3 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
   (export RUSTFLAGS="\"-C link-arg=-Wl,--warn-unresolved-symbols\""; \
     rm /android/ndk/arm && \
     ln -s /android/ndk/arm-14 /android/ndk/arm && \
-    python2.7 ../x.py dist --host $HOSTS --target $HOSTS)
+    python3 ../x.py dist --host $HOSTS --target $HOSTS)
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-i686-android/Dockerfile b/src/ci/docker/disabled/dist-i686-android/Dockerfile
index 04e83a431c4..b74dcefa351 100644
--- a/src/ci/docker/disabled/dist-i686-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-i686-android/Dockerfile
@@ -33,11 +33,11 @@ ENV RUST_CONFIGURE_ARGS \
 # build to finish we use --warn-unresolved-symbols. Note that the missing
 # symbols does not affect std, only the compiler (llvm) and cargo (openssl).
 ENV SCRIPT \
-  python2.7 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
+  python3 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
   (export RUSTFLAGS="\"-C link-arg=-Wl,--warn-unresolved-symbols\""; \
     rm /android/ndk/x86 && \
     ln -s /android/ndk/x86-14 /android/ndk/x86 && \
-    python2.7 ../x.py dist --host $HOSTS --target $HOSTS)
+    python3 ../x.py dist --host $HOSTS --target $HOSTS)
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile b/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
index 3227819dad5..19df9d6cf62 100644
--- a/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
+++ b/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=powerpc-unknown-linux-gnuspe
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile b/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
index 952c265a139..62d0bfc71b2 100644
--- a/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
+++ b/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=sparc64-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-x86_64-android/Dockerfile b/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
index 937301864cd..d44779763e5 100644
--- a/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
@@ -19,7 +19,7 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-cargo-openssl-static
 
-ENV SCRIPT python2.7 ../x.py dist --target $HOSTS --host $HOSTS
+ENV SCRIPT python3 ../x.py dist --target $HOSTS --host $HOSTS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile b/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
index dbff9e32e13..5b7196c573c 100644
--- a/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -33,4 +33,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-dragonfly
 
 ENV RUST_CONFIGURE_ARGS --enable-extended
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile b/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
index 440afd7c97f..5b65335bfe4 100644
--- a/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
@@ -18,7 +18,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   make \
   nasm \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   texinfo \
   wget \
@@ -46,4 +46,4 @@ ENV RUST_CONFIGURE_ARGS --disable-jemalloc \
   --set=$TARGET.cc=x86_64-unknown-haiku-gcc \
   --set=$TARGET.cxx=x86_64-unknown-haiku-g++ \
   --set=$TARGET.llvm-config=/bin/llvm-config-haiku
-ENV SCRIPT python2.7 ../x.py dist --host=$HOST --target=$HOST
+ENV SCRIPT python3 ../x.py dist --host=$HOST --target=$HOST
diff --git a/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile b/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
index 11a3acd68e3..7b53e73d700 100644
--- a/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
@@ -19,4 +19,4 @@ ENV \
     CXX_x86_64_unknown_redox=x86_64-unknown-redox-g++
 
 ENV RUST_CONFIGURE_ARGS --enable-extended
-ENV SCRIPT python2.7 ../x.py dist --target x86_64-unknown-redox
+ENV SCRIPT python3 ../x.py dist --target x86_64-unknown-redox
diff --git a/src/ci/docker/dist-aarch64-linux/Dockerfile b/src/ci/docker/dist-aarch64-linux/Dockerfile
index f5eb66ed714..37e81dffc06 100644
--- a/src/ci/docker/dist-aarch64-linux/Dockerfile
+++ b/src/ci/docker/dist-aarch64-linux/Dockerfile
@@ -36,4 +36,4 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-profiler \
       --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-android/Dockerfile b/src/ci/docker/dist-android/Dockerfile
index 64f31750dd7..6d38e199564 100644
--- a/src/ci/docker/dist-android/Dockerfile
+++ b/src/ci/docker/dist-android/Dockerfile
@@ -32,7 +32,7 @@ ENV RUST_CONFIGURE_ARGS \
       --x86_64-linux-android-ndk=/android/ndk/x86_64-21 \
       --disable-docs
 
-ENV SCRIPT python2.7 ../x.py dist --target $TARGETS
+ENV SCRIPT python3 ../x.py dist --target $TARGETS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/dist-arm-linux/Dockerfile b/src/ci/docker/dist-arm-linux/Dockerfile
index 50f7ca74e54..78f2734ed40 100644
--- a/src/ci/docker/dist-arm-linux/Dockerfile
+++ b/src/ci/docker/dist-arm-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_arm_unknown_linux_gnueabi=arm-unknown-linux-gnueabi-gcc \
 ENV HOSTS=arm-unknown-linux-gnueabi
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-armhf-linux/Dockerfile b/src/ci/docker/dist-armhf-linux/Dockerfile
index 209b6c166eb..175dadfd303 100644
--- a/src/ci/docker/dist-armhf-linux/Dockerfile
+++ b/src/ci/docker/dist-armhf-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_arm_unknown_linux_gnueabihf=arm-unknown-linux-gnueabihf-gcc \
 ENV HOSTS=arm-unknown-linux-gnueabihf
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-armv7-linux/Dockerfile b/src/ci/docker/dist-armv7-linux/Dockerfile
index f42a2bd8122..faa2ce10606 100644
--- a/src/ci/docker/dist-armv7-linux/Dockerfile
+++ b/src/ci/docker/dist-armv7-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_armv7_unknown_linux_gnueabihf=armv7-unknown-linux-gnueabihf-gcc \
 ENV HOSTS=armv7-unknown-linux-gnueabihf
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile b/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
index 61c363fbfd6..996fffeb871 100644
--- a/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
+++ b/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   xz-utils \
@@ -46,5 +46,5 @@ ENV CFLAGS_i586_unknown_linux_musl=-Wa,-mrelax-relocations=no
 ENV TARGETS=i586-unknown-linux-gnu,i686-unknown-linux-musl
 
 ENV SCRIPT \
-      python2.7 ../x.py test --target $TARGETS && \
-      python2.7 ../x.py dist --target $TARGETS,i586-unknown-linux-musl
+      python3 ../x.py test --target $TARGETS && \
+      python3 ../x.py dist --target $TARGETS,i586-unknown-linux-musl
diff --git a/src/ci/docker/dist-i686-freebsd/Dockerfile b/src/ci/docker/dist-i686-freebsd/Dockerfile
index 6f6a663a330..7978bb70869 100644
--- a/src/ci/docker/dist-i686-freebsd/Dockerfile
+++ b/src/ci/docker/dist-i686-freebsd/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -30,4 +30,4 @@ ENV \
 ENV HOSTS=i686-unknown-freebsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips-linux/Dockerfile b/src/ci/docker/dist-mips-linux/Dockerfile
index 466def1f80f..57a7fc25b5c 100644
--- a/src/ci/docker/dist-mips-linux/Dockerfile
+++ b/src/ci/docker/dist-mips-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips64-linux/Dockerfile b/src/ci/docker/dist-mips64-linux/Dockerfile
index 2205b733e99..63f1028e2be 100644
--- a/src/ci/docker/dist-mips64-linux/Dockerfile
+++ b/src/ci/docker/dist-mips64-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,4 +22,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips64-unknown-linux-gnuabi64
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips64el-linux/Dockerfile b/src/ci/docker/dist-mips64el-linux/Dockerfile
index f1d9dad46ea..a51edbc9c79 100644
--- a/src/ci/docker/dist-mips64el-linux/Dockerfile
+++ b/src/ci/docker/dist-mips64el-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips64el-unknown-linux-gnuabi64
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mipsel-linux/Dockerfile b/src/ci/docker/dist-mipsel-linux/Dockerfile
index ee73e29c76e..908cef90cef 100644
--- a/src/ci/docker/dist-mipsel-linux/Dockerfile
+++ b/src/ci/docker/dist-mipsel-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,4 +22,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mipsel-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc-linux/Dockerfile b/src/ci/docker/dist-powerpc-linux/Dockerfile
index 8c052db1b0d..b8792b0c7fa 100644
--- a/src/ci/docker/dist-powerpc-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc-linux/Dockerfile
@@ -35,4 +35,4 @@ ENV \
 ENV HOSTS=powerpc-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc64-linux/Dockerfile b/src/ci/docker/dist-powerpc64-linux/Dockerfile
index bb30210c056..a790a143ac5 100644
--- a/src/ci/docker/dist-powerpc64-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc64-linux/Dockerfile
@@ -36,4 +36,4 @@ ENV \
 ENV HOSTS=powerpc64-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc64le-linux/Dockerfile b/src/ci/docker/dist-powerpc64le-linux/Dockerfile
index ee9e4550483..5c17bc321c1 100644
--- a/src/ci/docker/dist-powerpc64le-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc64le-linux/Dockerfile
@@ -33,4 +33,4 @@ ENV \
 ENV HOSTS=powerpc64le-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-s390x-linux/Dockerfile b/src/ci/docker/dist-s390x-linux/Dockerfile
index 7ba6fe643c2..76d29a471c3 100644
--- a/src/ci/docker/dist-s390x-linux/Dockerfile
+++ b/src/ci/docker/dist-s390x-linux/Dockerfile
@@ -35,4 +35,4 @@ ENV \
 ENV HOSTS=s390x-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-various-1/Dockerfile b/src/ci/docker/dist-various-1/Dockerfile
index 4ac5e23d683..35b598e20f0 100644
--- a/src/ci/docker/dist-various-1/Dockerfile
+++ b/src/ci/docker/dist-various-1/Dockerfile
@@ -18,7 +18,6 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
   python3 \
   git \
   cmake \
@@ -209,8 +208,8 @@ ENV RUST_CONFIGURE_ARGS \
       --disable-docs
 
 ENV SCRIPT \
-      python2.7 ../x.py test --target $RUN_MAKE_TARGETS src/test/run-make && \
-      python2.7 ../x.py dist --target $TARGETS
+      python3 ../x.py test --target $RUN_MAKE_TARGETS src/test/run-make && \
+      python3 ../x.py dist --target $TARGETS
 
 # sccache
 COPY scripts/sccache.sh /scripts/
diff --git a/src/ci/docker/dist-various-2/Dockerfile b/src/ci/docker/dist-various-2/Dockerfile
index 5bb5436bec5..5864b5ffab2 100644
--- a/src/ci/docker/dist-various-2/Dockerfile
+++ b/src/ci/docker/dist-various-2/Dockerfile
@@ -17,7 +17,7 @@ RUN apt-get update && apt-get build-dep -y clang llvm && apt-get install -y --no
   libmpfr-dev \
   ninja-build \
   nodejs \
-  python2.7-dev \
+  python3-dev \
   software-properties-common \
   unzip \
   # Needed for apt-key to work:
@@ -110,4 +110,4 @@ ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs \
   --set target.wasm32-wasi.wasi-root=/wasm32-wasi \
   --musl-root-armv7=/musl-armv7
 
-ENV SCRIPT python2.7 ../x.py dist --target $TARGETS
+ENV SCRIPT python3 ../x.py dist --target $TARGETS
diff --git a/src/ci/docker/dist-x86_64-freebsd/Dockerfile b/src/ci/docker/dist-x86_64-freebsd/Dockerfile
index 698b81a92e9..12170a36614 100644
--- a/src/ci/docker/dist-x86_64-freebsd/Dockerfile
+++ b/src/ci/docker/dist-x86_64-freebsd/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -30,4 +30,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-freebsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-x86_64-musl/Dockerfile b/src/ci/docker/dist-x86_64-musl/Dockerfile
index 385eefde846..39316ea4486 100644
--- a/src/ci/docker/dist-x86_64-musl/Dockerfile
+++ b/src/ci/docker/dist-x86_64-musl/Dockerfile
@@ -7,7 +7,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   wget \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   xz-utils \
@@ -47,4 +47,4 @@ ENV CFLAGS_x86_64_unknown_linux_musl="-Wa,-mrelax-relocations=no -Wa,--compress-
     -Wl,--compress-debug-sections=none"
 
 # To run native tests replace `dist` below with `test`
-ENV SCRIPT python2.7 ../x.py dist --build $HOSTS
+ENV SCRIPT python3 ../x.py dist --build $HOSTS
diff --git a/src/ci/docker/dist-x86_64-netbsd/Dockerfile b/src/ci/docker/dist-x86_64-netbsd/Dockerfile
index 44b1aaa24b1..135bb33cef7 100644
--- a/src/ci/docker/dist-x86_64-netbsd/Dockerfile
+++ b/src/ci/docker/dist-x86_64-netbsd/Dockerfile
@@ -19,4 +19,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-netbsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/i686-gnu-nopt/Dockerfile b/src/ci/docker/i686-gnu-nopt/Dockerfile
index 517b59c38dc..c15b437e6d3 100644
--- a/src/ci/docker/i686-gnu-nopt/Dockerfile
+++ b/src/ci/docker/i686-gnu-nopt/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -18,7 +18,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
 
 # FIXME(#59637) takes too long on CI right now
 ENV NO_LLVM_ASSERTIONS=1 NO_DEBUG_ASSERTIONS=1
diff --git a/src/ci/docker/i686-gnu/Dockerfile b/src/ci/docker/i686-gnu/Dockerfile
index 03db3ba0995..377f07cef4e 100644
--- a/src/ci/docker/i686-gnu/Dockerfile
+++ b/src/ci/docker/i686-gnu/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -20,7 +20,7 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu
 # Exclude some tests that are unlikely to be platform specific, to speed up
 # this slow job.
-ENV SCRIPT python2.7 ../x.py test \
+ENV SCRIPT python3 ../x.py test \
   --exclude src/bootstrap \
   --exclude src/test/rustdoc-js \
   --exclude src/tools/error_index_generator \
diff --git a/src/ci/docker/mingw-check/Dockerfile b/src/ci/docker/mingw-check/Dockerfile
index 1293717f975..17d844a1f99 100644
--- a/src/ci/docker/mingw-check/Dockerfile
+++ b/src/ci/docker/mingw-check/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,9 +22,9 @@ RUN sh /scripts/sccache.sh
 COPY mingw-check/validate-toolstate.sh /scripts/
 
 ENV RUN_CHECK_WITH_PARALLEL_QUERIES 1
-ENV SCRIPT python2.7 ../x.py test src/tools/expand-yaml-anchors && \
-           python2.7 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
-           python2.7 ../x.py build --stage 0 src/tools/build-manifest && \
-           python2.7 ../x.py test --stage 0 src/tools/compiletest && \
-           python2.7 ../x.py test src/tools/tidy && \
+ENV SCRIPT python3 ../x.py test src/tools/expand-yaml-anchors && \
+           python3 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
+           python3 ../x.py build --stage 0 src/tools/build-manifest && \
+           python3 ../x.py test --stage 0 src/tools/compiletest && \
+           python3 ../x.py test src/tools/tidy && \
            /scripts/validate-toolstate.sh
diff --git a/src/ci/docker/mingw-check/validate-toolstate.sh b/src/ci/docker/mingw-check/validate-toolstate.sh
index 2ebf1d6d5ae..c6d728eb80d 100755
--- a/src/ci/docker/mingw-check/validate-toolstate.sh
+++ b/src/ci/docker/mingw-check/validate-toolstate.sh
@@ -7,12 +7,12 @@ IFS=$'\n\t'
 rm -rf rust-toolstate
 git clone --depth=1 https://github.com/rust-lang-nursery/rust-toolstate.git
 cd rust-toolstate
-python2.7 "../../src/tools/publish_toolstate.py" "$(git rev-parse HEAD)" \
+python3 "../../src/tools/publish_toolstate.py" "$(git rev-parse HEAD)" \
     "$(git log --format=%s -n1 HEAD)" "" ""
 # Only check maintainers if this build is supposed to publish toolstate.
 # Builds that are not supposed to publish don't have the access token.
 if [ -n "${TOOLSTATE_PUBLISH+is_set}" ]; then
-  TOOLSTATE_VALIDATE_MAINTAINERS_REPO=rust-lang/rust python2.7 \
+  TOOLSTATE_VALIDATE_MAINTAINERS_REPO=rust-lang/rust python3 \
       "../../src/tools/publish_toolstate.py"
 fi
 cd ..
diff --git a/src/ci/docker/scripts/android-base-apt-get.sh b/src/ci/docker/scripts/android-base-apt-get.sh
index 738410c58fc..391b68ea637 100644
--- a/src/ci/docker/scripts/android-base-apt-get.sh
+++ b/src/ci/docker/scripts/android-base-apt-get.sh
@@ -11,7 +11,7 @@ apt-get install -y --no-install-recommends \
   libssl-dev \
   make \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   unzip \
   xz-utils
diff --git a/src/ci/docker/scripts/android-ndk.sh b/src/ci/docker/scripts/android-ndk.sh
index 0db30e420e3..dafcb3cb7a7 100644
--- a/src/ci/docker/scripts/android-ndk.sh
+++ b/src/ci/docker/scripts/android-ndk.sh
@@ -13,7 +13,7 @@ download_ndk() {
 
 make_standalone_toolchain() {
     # See https://developer.android.com/ndk/guides/standalone_toolchain.htm
-    python2.7 /android/ndk/ndk/build/tools/make_standalone_toolchain.py \
+    python3 /android/ndk/ndk/build/tools/make_standalone_toolchain.py \
         --install-dir /android/ndk/$1-$2 \
         --arch $1 \
         --api $2
diff --git a/src/ci/docker/scripts/cross-apt-packages.sh b/src/ci/docker/scripts/cross-apt-packages.sh
index bb72e33def2..7030cd74cae 100644
--- a/src/ci/docker/scripts/cross-apt-packages.sh
+++ b/src/ci/docker/scripts/cross-apt-packages.sh
@@ -19,7 +19,7 @@ apt-get update && apt-get install -y --no-install-recommends \
   make \
   patch \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   texinfo \
   unzip \
diff --git a/src/ci/docker/test-various/Dockerfile b/src/ci/docker/test-various/Dockerfile
index 6a2600d8756..9276e4ed82d 100644
--- a/src/ci/docker/test-various/Dockerfile
+++ b/src/ci/docker/test-various/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -40,7 +40,7 @@ ENV RUST_CONFIGURE_ARGS \
 ENV NO_DEBUG_ASSERTIONS=1
 
 ENV WASM_TARGETS=wasm32-unknown-unknown
-ENV WASM_SCRIPT python2.7 /checkout/x.py test --target $WASM_TARGETS \
+ENV WASM_SCRIPT python3 /checkout/x.py test --target $WASM_TARGETS \
   src/test/run-make \
   src/test/ui \
   src/test/compile-fail \
@@ -49,13 +49,13 @@ ENV WASM_SCRIPT python2.7 /checkout/x.py test --target $WASM_TARGETS \
   src/libcore
 
 ENV NVPTX_TARGETS=nvptx64-nvidia-cuda
-ENV NVPTX_SCRIPT python2.7 /checkout/x.py test --target $NVPTX_TARGETS \
+ENV NVPTX_SCRIPT python3 /checkout/x.py test --target $NVPTX_TARGETS \
   src/test/run-make \
   src/test/assembly
 
 ENV MUSL_TARGETS=x86_64-unknown-linux-musl \
     CC_x86_64_unknown_linux_musl=x86_64-linux-musl-gcc \
     CXX_x86_64_unknown_linux_musl=x86_64-linux-musl-g++
-ENV MUSL_SCRIPT python2.7 /checkout/x.py test --target $MUSL_TARGETS
+ENV MUSL_SCRIPT python3 /checkout/x.py test --target $MUSL_TARGETS
 
 ENV SCRIPT $WASM_SCRIPT && $NVPTX_SCRIPT && $MUSL_SCRIPT
diff --git a/src/ci/docker/wasm32/Dockerfile b/src/ci/docker/wasm32/Dockerfile
index a0f35afd995..91c492d03c1 100644
--- a/src/ci/docker/wasm32/Dockerfile
+++ b/src/ci/docker/wasm32/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -20,6 +20,9 @@ RUN bash /scripts/emscripten.sh
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+# emcc seems to need python to specifically be "python" and not "python3"
+RUN ln `which python3` /usr/bin/python
+
 ENV PATH=$PATH:/emsdk-portable
 ENV PATH=$PATH:/emsdk-portable/upstream/emscripten/
 ENV PATH=$PATH:/emsdk-portable/node/12.9.1_64bit/bin/
@@ -35,7 +38,7 @@ ENV NO_CHANGE_USER=1
 
 # FIXME: Re-enable these tests once https://github.com/rust-lang/cargo/pull/7476
 # is picked up by CI
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS \
+ENV SCRIPT python3 ../x.py test --target $TARGETS \
     --exclude src/libcore \
     --exclude src/liballoc \
     --exclude src/libproc_macro \
diff --git a/src/ci/docker/x86_64-gnu-aux/Dockerfile b/src/ci/docker/x86_64-gnu-aux/Dockerfile
index 44bee199911..86ac0256d28 100644
--- a/src/ci/docker/x86_64-gnu-aux/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-aux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   libssl-dev \
diff --git a/src/ci/docker/x86_64-gnu-debug/Dockerfile b/src/ci/docker/x86_64-gnu-debug/Dockerfile
index 890e13232c3..c5e41b8a75a 100644
--- a/src/ci/docker/x86_64-gnu-debug/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-debug/Dockerfile
@@ -6,8 +6,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
-  python2.7-dev \
+  python3 \
+  python3-dev \
   libxml2-dev \
   libncurses-dev \
   libedit-dev \
@@ -40,5 +40,5 @@ ENV RUST_CONFIGURE_ARGS \
       --set target.x86_64-unknown-linux-gnu.cxx=clang++
 
 ENV SCRIPT \
-  python2.7 ../x.py build && \
-  python2.7 ../x.py test src/test/run-make-fulldeps --test-args clang
+  python3 ../x.py build && \
+  python3 ../x.py test src/test/run-make-fulldeps --test-args clang
diff --git a/src/ci/docker/x86_64-gnu-distcheck/Dockerfile b/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
index 364f45aba2c..cc07a591cc1 100644
--- a/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -19,7 +19,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu --set rust.ignore-git=false
-ENV SCRIPT python2.7 ../x.py test distcheck
+ENV SCRIPT python3 ../x.py test distcheck
 ENV DIST_SRC 1
 
 # The purpose of this builder is to test that we can `./x.py test` successfully
diff --git a/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile b/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
index 207f972c3cd..de7ee6950b5 100644
--- a/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -21,7 +21,7 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
       --enable-full-bootstrap
-ENV SCRIPT python2.7 ../x.py build
+ENV SCRIPT python3 ../x.py build
 
 # In general this just slows down the build and we're just a smoke test that
 # a full bootstrap works in general, so there's not much need to take this
diff --git a/src/ci/docker/x86_64-gnu-nopt/Dockerfile b/src/ci/docker/x86_64-gnu-nopt/Dockerfile
index 6a5c7f5d9e6..096f67e13d1 100644
--- a/src/ci/docker/x86_64-gnu-nopt/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-nopt/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -21,4 +21,4 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
   --disable-optimize-tests \
   --set rust.test-compare-mode
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
diff --git a/src/ci/docker/x86_64-gnu-tools/Dockerfile b/src/ci/docker/x86_64-gnu-tools/Dockerfile
index 51193402ee8..148e09f6ad1 100644
--- a/src/ci/docker/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-tools/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   libssl-dev \
diff --git a/src/ci/docker/x86_64-gnu-tools/checktools.sh b/src/ci/docker/x86_64-gnu-tools/checktools.sh
index 72325c7b948..00ac20c08dc 100755
--- a/src/ci/docker/x86_64-gnu-tools/checktools.sh
+++ b/src/ci/docker/x86_64-gnu-tools/checktools.sh
@@ -7,7 +7,7 @@ X_PY="$1"
 # Try to test all the tools and store the build/test success in the TOOLSTATE_FILE
 
 set +e
-python2.7 "$X_PY" test --no-fail-fast \
+python3 "$X_PY" test --no-fail-fast \
     src/doc/book \
     src/doc/nomicon \
     src/doc/reference \
@@ -22,4 +22,4 @@ python2.7 "$X_PY" test --no-fail-fast \
 
 set -e
 
-python2.7 "$X_PY" test check-tools
+python3 "$X_PY" test check-tools
diff --git a/src/ci/docker/x86_64-gnu/Dockerfile b/src/ci/docker/x86_64-gnu/Dockerfile
index b864c09ea8c..af6e1318062 100644
--- a/src/ci/docker/x86_64-gnu/Dockerfile
+++ b/src/ci/docker/x86_64-gnu/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ ENV RUST_CONFIGURE_ARGS \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
diff --git a/src/ci/run.sh b/src/ci/run.sh
index 73c3a964f53..59f2736cbd4 100755
--- a/src/ci/run.sh
+++ b/src/ci/run.sh
@@ -23,6 +23,14 @@ fi
 ci_dir=`cd $(dirname $0) && pwd`
 source "$ci_dir/shared.sh"
 
+if command -v python > /dev/null; then
+    PYTHON="python"
+elif command -v python3 > /dev/null; then
+    PYTHON="python3"
+else
+    PYTHON="python2"
+fi
+
 if ! isCI || isCiBranch auto || isCiBranch beta; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set build.print-step-timings --enable-verbose-tests"
 fi
@@ -107,7 +115,7 @@ SCCACHE_IDLE_TIMEOUT=10800 sccache --start-server || true
 
 if [ "$RUN_CHECK_WITH_PARALLEL_QUERIES" != "" ]; then
   $SRC/configure --enable-parallel-compiler
-  CARGO_INCREMENTAL=0 python2.7 ../x.py check
+  CARGO_INCREMENTAL=0 $PYTHON ../x.py check
   rm -f config.toml
   rm -rf build
 fi
diff --git a/src/ci/scripts/install-mingw.sh b/src/ci/scripts/install-mingw.sh
index 78728dd7d00..ae85d5cab01 100755
--- a/src/ci/scripts/install-mingw.sh
+++ b/src/ci/scripts/install-mingw.sh
@@ -50,8 +50,9 @@ if isWindows; then
     esac
 
     if [[ "${CUSTOM_MINGW-0}" -ne 1 ]]; then
-        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain \
-            mingw-w64-$arch-cmake mingw-w64-$arch-gcc mingw-w64-$arch-python2
+        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain mingw-w64-$arch-cmake \
+            mingw-w64-$arch-gcc \
+            mingw-w64-$arch-python # the python package is actually for python3
         ciCommandAddPath "$(ciCheckoutPath)/msys2/mingw${bits}/bin"
     else
         mingw_dir="mingw${bits}"
diff --git a/src/ci/scripts/install-msys2-packages.sh b/src/ci/scripts/install-msys2-packages.sh
index 22b9854ad5e..3874a86e120 100755
--- a/src/ci/scripts/install-msys2-packages.sh
+++ b/src/ci/scripts/install-msys2-packages.sh
@@ -13,7 +13,7 @@ if isWindows; then
     # one way or another. The msys interpreters seem to have weird path conversions
     # baked in which break LLVM's build system one way or another, so let's use the
     # native version which keeps everything as native as possible.
-    python_home="C:/hostedtoolcache/windows/Python/2.7.17/x64"
-    cp "${python_home}/python.exe" "${python_home}/python2.7.exe"
-    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\2.7.17\\x64"
+    python_home="C:/hostedtoolcache/windows/Python/3.7.6/x64"
+    cp "${python_home}/python.exe" "${python_home}/python3.exe"
+    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\3.7.6\\x64"
 fi
diff --git a/src/etc/dec2flt_table.py b/src/etc/dec2flt_table.py
index 4979882ffea..9bbcaf7c4cc 100755
--- a/src/etc/dec2flt_table.py
+++ b/src/etc/dec2flt_table.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python3
 
 """
 Generate powers of ten using William Clinger's ``AlgorithmM`` for use in
diff --git a/src/etc/test-float-parse/runtests.py b/src/etc/test-float-parse/runtests.py
index 852bc775896..fe6fd45f9a5 100644
--- a/src/etc/test-float-parse/runtests.py
+++ b/src/etc/test-float-parse/runtests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python3
 
 """
 Testing dec2flt
diff --git a/src/test/run-make-fulldeps/sysroot-crates-are-unstable/Makefile b/src/test/run-make-fulldeps/sysroot-crates-are-unstable/Makefile
index a35174b3c2a..1e267fb9576 100644
--- a/src/test/run-make-fulldeps/sysroot-crates-are-unstable/Makefile
+++ b/src/test/run-make-fulldeps/sysroot-crates-are-unstable/Makefile
@@ -1,2 +1,2 @@
 all:
-	python2.7 test.py
+	'$(PYTHON)' test.py
diff --git a/src/tools/publish_toolstate.py b/src/tools/publish_toolstate.py
index b55ead088ca..307239fa4c9 100755
--- a/src/tools/publish_toolstate.py
+++ b/src/tools/publish_toolstate.py
@@ -57,6 +57,13 @@ REPOS = {
     'rustc-dev-guide': 'https://github.com/rust-lang/rustc-dev-guide',
 }
 
+def load_json_from_response(resp):
+    content = resp.read()
+    if isinstance(content, bytes):
+        content = content.decode('utf-8')
+    else:
+        print("Refusing to decode " + str(type(content)) + " to str")
+    return json.loads(content)
 
 def validate_maintainers(repo, github_token):
     '''Ensure all maintainers are assignable on a GitHub repo'''
@@ -71,7 +78,7 @@ def validate_maintainers(repo, github_token):
             # Properly load nested teams.
             'Accept': 'application/vnd.github.hellcat-preview+json',
         }))
-        assignable.extend(user['login'] for user in json.load(response))
+        assignable.extend(user['login'] for user in load_json_from_response(response))
         # Load the next page if available
         url = None
         link_header = response.headers.get('Link')
@@ -176,7 +183,7 @@ def update_latest(
 ):
     '''Updates `_data/latest.json` to match build result of the given commit.
     '''
-    with open('_data/latest.json', 'rb+') as f:
+    with open('_data/latest.json', 'r+') as f:
         latest = json.load(f, object_pairs_hook=collections.OrderedDict)
 
         current_status = {