diff --git a/README.rst b/README.rst
index eaa0873f3..079ec88b3 100644
--- a/README.rst
+++ b/README.rst
@@ -176,9 +176,7 @@ and you can unpack them to ~/.local/share/fish/install/ (currently, subject to c
 
 You will have to use ``--install`` once per user and you will have to run it again when you upgrade fish. It will tell you to.
 
-To install fish as self-installable, just use ``cargo``, like:
-
-.. code:: bash
+To install fish as self-installable, just use ``cargo``, like::
 
    cargo install --path /path/to/fish # if you have a git clone
    cargo install --git https://github.com/fish-shell/fish-shell --tag 4.0 # to build from git once 4.0 is released
@@ -188,6 +186,10 @@ This will place the binaries in ``~/.cargo/bin/``, but you can place them wherev
 
 This build won't have the HTML docs (``help`` will open the online version) or translations.
 
+It requires sphinx by default, if sphinx-build is not available you can build without man pages by running it with $FISH_BUILD_DOCS set to 0::
+
+  FISH_BUILD_DOCS=0 cargo install --path .
+
 You can also link it statically (but not against glibc) and move it to other computers.
 
 Contributing Changes to the Code
diff --git a/build.rs b/build.rs
index 415a171bd..f812e390f 100644
--- a/build.rs
+++ b/build.rs
@@ -362,22 +362,43 @@ fn build_man(build_dir: &Path) {
     ];
     let _ = std::fs::create_dir_all(sec1dir.to_str().unwrap());
 
-    match Command::new("sphinx-build").args(args).output() {
+    rsconf::rebuild_if_env_changed("FISH_BUILD_DOCS");
+    if env::var("FISH_BUILD_DOCS") == Ok("0".to_string()) {
+        println!("cargo:warning=Skipping man pages because $FISH_BUILD_DOCS is set to 0");
+        return;
+    }
+
+    // We run sphinx to build the man pages.
+    // Every error here is fatal so cargo doesn't cache the result
+    // - if we skipped the docs with sphinx not installed, installing it would not then build the docs.
+    // That means you need to explicitly set $FISH_BUILD_DOCS=0 (`FISH_BUILD_DOCS=0 cargo install --path .`),
+    // which is unfortunate - but the docs are pretty important because they're also used for --help.
+    match Command::new("sphinx-build").args(args).spawn() {
+        Err(x) if x.kind() == std::io::ErrorKind::NotFound => {
+            panic!("Could not find sphinx-build to build man pages.\nInstall sphinx or disable building the docs by setting $FISH_BUILD_DOCS=0.");
+        }
         Err(x) => {
-            println!("cargo:warning=Could not build man pages: {:?}", x);
+            // Another error - permissions wrong etc
+            panic!(
+                "Error starting sphinx-build to build man pages: {:?}",
+                x
+            );
         }
-        Ok(x) => {
-            if !x.status.success() {
-                println!(
-                    "cargo:warning=Could not build man pages: {:?}",
-                    std::str::from_utf8(&x.stdout).unwrap()
+        Ok(mut x) => match x.wait() {
+            Err(err) => {
+                panic!(
+                    "Error waiting for sphinx-build to build man pages: {:?}",
+                    err
                 );
-                println!(
-                    "cargo:warning=Could not build man pages: {:?}",
-                    std::str::from_utf8(&x.stderr).unwrap()
-                );
-                panic!("Building docs failed");
             }
-        }
+            Ok(out) => {
+                if out.success() {
+                    // Success!
+                    return;
+                } else {
+                    panic!("sphinx-build failed to build the man pages.");
+                }
+            }
+        },
     }
 }