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
@@ -113,11 +113,20 @@
 
   demanglePath(rust_demangle::InType::No);
 
-  if (Position != Input.size()) {
+  if (Position != Input.size() && look() != '.') {
     SwapAndRestore<bool> SavePrint(Print, false);
     demanglePath(InType::No);
   }
 
+  // An extension allowing an arbitrary dot suffix.
+  if (consumeIf('.')) {
+    auto Suffix = Input.substr(Position);
+    Position += Suffix.size();
+    print(" (");
+    print(Suffix);
+    print(")");
+  }
+
   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
@@ -448,6 +448,14 @@
 CHECK: _RIC7backrefKBa_E
        _RIC7backrefKBa_E
 
+; Dot suffix
+
+CHECK: dot (llvm.1234)
+       _RC3dot.llvm.1234
+
+CHECK: dot (llvm.6789)
+       _RC3dotC5crate.llvm.6789
+
 ; Invalid mangled characters
 
 CHECK: _RNvC2a.1c