diff --git a/llvm/lib/Demangle/RustDemangle.cpp b/llvm/lib/Demangle/RustDemangle.cpp
--- a/llvm/lib/Demangle/RustDemangle.cpp
+++ b/llvm/lib/Demangle/RustDemangle.cpp
@@ -113,7 +113,10 @@
 
   demanglePath(rust_demangle::InType::No);
 
-  // FIXME parse optional <instantiating-crate>.
+  if (Position != Input.size()) {
+    SwapAndRestore<bool> SavePrint(Print, false);
+    demanglePath(InType::No);
+  }
 
   if (Position != Input.size())
     Error = true;
diff --git a/llvm/test/Demangle/rust.test b/llvm/test/Demangle/rust.test
--- a/llvm/test/Demangle/rust.test
+++ b/llvm/test/Demangle/rust.test
@@ -9,6 +9,11 @@
 CHECK: a::b::c
        _RNvNvC1a1b1c
 
+; Instantiating crate
+
+CHECK: crate
+       _RC5crateC3foo
+
 ; Closure namespace
 
 CHECK: crate::{closure#0}