diff --git a/llvm/include/llvm/Demangle/RustDemangle.h b/llvm/include/llvm/Demangle/RustDemangle.h
--- a/llvm/include/llvm/Demangle/RustDemangle.h
+++ b/llvm/include/llvm/Demangle/RustDemangle.h
@@ -84,11 +84,13 @@
   bool demangle(StringView MangledName);
 
 private:
-  void demanglePath(InType InType);
+  bool demanglePath(InType InType, bool LeaveOpen = false);
   void demangleImplPath(InType InType);
   void demangleGenericArg();
   void demangleType();
   void demangleFnSig();
+  void demangleDynBounds();
+  void demangleDynTrait();
   void demangleBinder();
   void demangleConst();
   void demangleConstInt();
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
@@ -121,7 +121,10 @@
   return !Error;
 }
 
-// Demangles a path. InType indicates whether a path is inside a type.
+// Demangles a path. InType indicates whether a path is inside a type. When
+// LeaveOpen is true, a closing `>` after generic arguments is omitted from the
+// output. Return value indicates whether generics arguments have been left
+// open.
 //
 // <path> = "C" <identifier>               // crate root
 //        | "M" <impl-path> <type>         // <T> (inherent impl)
@@ -135,12 +138,13 @@
 //      | "S"      // shim
 //      | <A-Z>    // other special namespaces
 //      | <a-z>    // internal namespaces
-void Demangler::demanglePath(InType InType) {
+bool Demangler::demanglePath(InType InType, bool LeaveOpen) {
   if (Error || RecursionLevel >= MaxRecursionLevel) {
     Error = true;
-    return;
+    return false;
   }
   SwapAndRestore<size_t> SaveRecursionLevel(RecursionLevel, RecursionLevel + 1);
+  bool IsOpen = false;
 
   switch (consume()) {
   case 'C': {
@@ -220,7 +224,10 @@
         print(", ");
       demangleGenericArg();
     }
-    print(">");
+    if (LeaveOpen)
+      IsOpen = true;
+    else
+      print(">");
     break;
   }
   default:
@@ -228,6 +235,8 @@
     Error = true;
     break;
   }
+
+  return IsOpen;
 }
 
 // <impl-path> = [<disambiguator>] <path>
@@ -480,6 +489,17 @@
   case 'F':
     demangleFnSig();
     break;
+  case 'D':
+    demangleDynBounds();
+    if (consumeIf('L')) {
+      if (auto Lifetime = parseBase62Number()) {
+        print(" + ");
+        printLifetime(Lifetime);
+      }
+    } else {
+      Error = true;
+    }
+    break;
   default:
     Position = Start;
     demanglePath(rust_demangle::InType::Yes);
@@ -529,6 +549,37 @@
   }
 }
 
+// <dyn-bounds> = [<binder>] {<dyn-trait>} "E"
+void Demangler::demangleDynBounds() {
+  SwapAndRestore<size_t> SaveBoundLifetimes(BoundLifetimes, BoundLifetimes);
+  print("dyn ");
+  demangleBinder();
+  for (size_t I = 0; !Error && !consumeIf('E'); ++I) {
+    if (I > 0)
+      print(" + ");
+    demangleDynTrait();
+  }
+}
+
+// <dyn-trait> = <path> {<dyn-trait-assoc-binding>}
+// <dyn-trait-assoc-binding> = "p" <undisambiguated-identifier> <type>
+void Demangler::demangleDynTrait() {
+  bool IsOpen = demanglePath(InType::Yes, true /* LeaveOpen */);
+  while (!Error && consumeIf('p')) {
+    if (!IsOpen) {
+      IsOpen = true;
+      print('<');
+    } else {
+      print(", ");
+    }
+    print(parseIdentifier().Name);
+    print(" = ");
+    demangleType();
+  }
+  if (IsOpen)
+    print(">");
+}
+
 // Demangles optional binder and updates the number of bound lifetimes.
 //
 // <binder> = ["G" <base-62-number>]
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
@@ -232,6 +232,31 @@
 CHECK: function::<unsafe extern "C-cmse-nonsecure-call" fn()>
        _RIC8functionFUK21C_cmse_nonsecure_callEuE
 
+; Trait objects
+
+CHECK: trait::<dyn Display>
+       _RIC5traitDC7DisplayEL_E
+
+CHECK: trait::<dyn Display + Send + Sync>
+       _RIC5traitDC7DisplayC4SendC4SyncEL_E
+
+CHECK: trait::<dyn Iterator<_, Item = _>>
+       _RIC5traitDIC8IteratorpEp4ItempEL_E
+
+CHECK: trait::<dyn Iterator<Item = _>>
+       _RIC5traitDC8Iteratorp4ItempEL_E
+
+CHECK: trait::<dyn for<'a> Display>
+       _RIC5traitDG_C7DisplayEL_E
+
+CHECK: trait::<dyn for<'a> Foo<dyn for<'b> Bar + 'a>>
+       _RIC5traitDG_IC3FooDG_C3BarEL0_EEL_E
+
+; Invalid trait object, missing lifetime.
+
+CHECK: _RIC5traitDC7DisplayEE
+       _RIC5traitDC7DisplayEE
+
 ; Binders
 
 CHECK: binders::<for<'a> fn(&'a _)>