diff --git a/README.md b/README.md
index 83004fc..7ac9eac 100644
--- a/README.md
+++ b/README.md
@@ -128,6 +128,22 @@
 To change this behavior, set the environmental variables `FARGO_CARGO` and `FARGO_RUSTC` before
 running fargo.
 
+## Environmental variables set by fargo
+
+CARGO\_TARGET\_[X86\_64|AARCH64]\_UNKNOWN\_FUCHSIA\_RUNNER - set to the fargo binary to run remotely on simulator or device.
+
+CARGO\_TARGET\_[X86\_64|AARCH64]\_UNKNOWN\_FUCHSIA\_RUSTFLAGS - set to provide linker flags
+
+CARGO\_TARGET\_[X86\_64|AARCH64]\_UNKNOWN\_FUCHSIA\_LINKER - set to specify the linker
+
+RUSTC - set to cause cargo to use the copy of rustc in buildtools
+
+RUSTDOC - set to cause cargo to use the copy of rustdoc in buildtools
+
+FUCHSIA\_SHARED\_ROOT - set to the directory containing shared libraries for the current selected architecture. Useful for build scripts.
+
+ZIRCON\_BUILD\_ROOT - set to the zircon build directory for the current architecture. Useful for build scripts.
+
 ## Using crates that link with native libraries
 
 Some crates are wrappers around libraries written in other languages. An
diff --git a/src/lib.rs b/src/lib.rs
index e2b2f3c..4ae9f80 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -25,9 +25,8 @@
 use failure::{err_msg, Error, ResultExt};
 pub use sdk::TargetOptions;
 use sdk::{cargo_out_dir, cargo_path, clang_archiver_path, clang_c_compiler_path,
-          clang_cpp_compiler_path, clang_linker_path, clang_ranlib_path, fidl2_target_gen_dir,
-          rustc_path, rustdoc_path, shared_libraries_path, sysroot_path, target_gen_dir,
-          FuchsiaConfig};
+          clang_cpp_compiler_path, clang_linker_path, clang_ranlib_path, rustc_path, rustdoc_path,
+          shared_libraries_path, sysroot_path, zircon_build_path, FuchsiaConfig};
 use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
@@ -217,7 +216,7 @@
 }
 
 fn build_doc(
-    run_cargo_options: RunCargoOptions, target_options: &TargetOptions, no_deps: bool, open: bool
+    run_cargo_options: RunCargoOptions, target_options: &TargetOptions, no_deps: bool, open: bool,
 ) -> Result<(), Error> {
     let mut args = vec![];
     if no_deps {
@@ -444,8 +443,11 @@
         )
         .env("RUSTC", rustc_path(target_options)?.to_str().unwrap())
         .env("RUSTDOC", rustdoc_path(target_options)?.to_str().unwrap())
-        .env("FUCHSIA_GEN_ROOT", target_gen_dir(target_options)?)
-        .env("FIDL_GEN_ROOT", fidl2_target_gen_dir(target_options)?)
+        .env(
+            "FUCHSIA_SHARED_ROOT",
+            shared_libraries_path(target_options)?,
+        )
+        .env("ZIRCON_BUILD_ROOT", zircon_build_path(target_options)?)
         .arg(subcommand)
         .args(target_args)
         .args(args);
diff --git a/src/sdk.rs b/src/sdk.rs
index cf1aebe..0220801 100644
--- a/src/sdk.rs
+++ b/src/sdk.rs
@@ -116,16 +116,6 @@
     possible_target_out_dir(&fuchsia_dir, options)
 }
 
-pub fn target_gen_dir(options: &TargetOptions) -> Result<PathBuf, Error> {
-    let target_out_dir = target_out_dir(options)?;
-    Ok(target_out_dir.join("gen"))
-}
-
-pub fn fidl2_target_gen_dir(options: &TargetOptions) -> Result<PathBuf, Error> {
-    let target_out_dir = target_out_dir(options)?;
-    Ok(target_out_dir.join("fidling/gen"))
-}
-
 pub fn cargo_out_dir(options: &TargetOptions) -> Result<PathBuf, Error> {
     let fuchsia_dir = fuchsia_dir(options)?;
     let target_triple = format!("{}-unknown-fuchsia", options.target_cpu_linker);
@@ -147,6 +137,20 @@
         .join("sysroot"))
 }
 
+pub fn zircon_build_path(options: &TargetOptions) -> Result<PathBuf, Error> {
+    let fuchsia_dir = fuchsia_dir(options)?;
+    let build_name = if options.target_cpu == X64 {
+        "build-x64"
+    } else {
+        "build-arm64"
+    };
+    let zircon_build = fuchsia_dir
+        .join("out")
+        .join("build-zircon")
+        .join(build_name);
+    Ok(zircon_build)
+}
+
 pub fn shared_libraries_path(options: &TargetOptions) -> Result<PathBuf, Error> {
     let shared_name = if options.target_cpu == X64 {
         "x64-shared"