diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3333,6 +3333,9 @@
       if (!Func->hasParamAttribute(i, Kind))
         continue;
 
+      if (Func->getParamAttribute(i, Kind).getValueAsType())
+        continue;
+
       Func->removeParamAttr(i, Kind);
 
       Type *PTy = cast<FunctionType>(FTy)->getParamType(i);
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -1045,6 +1045,11 @@
     if (Entry == 0) {
       AttributeGroups.push_back(Pair);
       Entry = AttributeGroups.size();
+
+      for (Attribute Attr : AS) {
+        if (Attr.isTypeAttribute())
+          EnumerateType(Attr.getValueAsType());
+      }
     }
   }
 }
diff --git a/llvm/test/Assembler/opaque-ptr.ll b/llvm/test/Assembler/opaque-ptr.ll
--- a/llvm/test/Assembler/opaque-ptr.ll
+++ b/llvm/test/Assembler/opaque-ptr.ll
@@ -141,3 +141,8 @@
     cleanup
   ret void
 }
+
+; CHECK: define void @byval(ptr byval({ i32, i32 }) %0)
+define void @byval(ptr byval({ i32, i32 }) %0) {
+  ret void
+}