AIX searches dynamic libraries in LIBPATH.

crates/cargo-util/src/paths.rs

@@ -55,6 +55,8 @@ pub fn dylib_path_envvar() -> &'static str {
         // penalty starting in 10.13. Cargo's testsuite ran more than twice as
         // slow with it on CI.
         "DYLD_FALLBACK_LIBRARY_PATH"
+    } else if cfg!(target_os = "aix") {
+        "LIBPATH"
     } else {
         "LD_LIBRARY_PATH"
     }

src/doc/src/reference/environment-variables.md

@@ -274,6 +274,7 @@ on the platform:
 * Windows: `PATH`
 * macOS: `DYLD_FALLBACK_LIBRARY_PATH`
 * Unix: `LD_LIBRARY_PATH`
+* AIX: `LIBPATH`
 
 The value is extended from the existing value when Cargo starts. macOS has
 special consideration where if `DYLD_FALLBACK_LIBRARY_PATH` is not already