Index: lib/IR/Core.cpp
===================================================================
--- lib/IR/Core.cpp
+++ lib/IR/Core.cpp
@@ -1842,6 +1842,8 @@
 
 unsigned LLVMGetAttributeCountAtIndex(LLVMValueRef F, LLVMAttributeIndex Idx) {
   auto *ASN = AttributeSetNode::get(unwrap<Function>(F)->getAttributes(), Idx);
+  if (!ASN)
+    return 0;
   return ASN->getNumAttributes();
 }
 
@@ -2173,6 +2175,8 @@
                                        LLVMAttributeIndex Idx) {
   auto CS = CallSite(unwrap<Instruction>(C));
   auto *ASN = AttributeSetNode::get(CS.getAttributes(), Idx);
+  if (!ASN)
+    return 0;
   return ASN->getNumAttributes();
 }
 
Index: tools/llvm-c-test/echo.cpp
===================================================================
--- tools/llvm-c-test/echo.cpp
+++ tools/llvm-c-test/echo.cpp
@@ -379,11 +379,13 @@
     auto Ctx = LLVMGetModuleContext(M);
     int ArgCount = LLVMGetNumArgOperands(Src);
     for (int i = LLVMAttributeReturnIndex; i <= ArgCount; i++) {
-      for (unsigned k = 0, e = LLVMGetLastEnumAttributeKind(); k < e; ++k) {
-        if (auto SrcA = LLVMGetCallSiteEnumAttribute(Src, i, k)) {
-          auto Val = LLVMGetEnumAttributeValue(SrcA);
-          auto A = LLVMCreateEnumAttribute(Ctx, k, Val);
-          LLVMAddCallSiteAttribute(Dst, i, A);
+      if (LLVMGetCallSiteAttributeCount(Src, i) > 0) {
+        for (unsigned k = 0, e = LLVMGetLastEnumAttributeKind(); k < e; ++k) {
+          if (auto SrcA = LLVMGetCallSiteEnumAttribute(Src, i, k)) {
+            auto Val = LLVMGetEnumAttributeValue(SrcA);
+            auto A = LLVMCreateEnumAttribute(Ctx, k, Val);
+            LLVMAddCallSiteAttribute(Dst, i, A);
+          }
         }
       }
     }
@@ -812,11 +814,13 @@
     // Copy attributes
     for (int i = LLVMAttributeFunctionIndex, c = LLVMCountParams(F);
          i <= c; ++i) {
-      for (unsigned k = 0, e = LLVMGetLastEnumAttributeKind(); k < e; ++k) {
-        if (auto SrcA = LLVMGetEnumAttributeAtIndex(Cur, i, k)) {
-          auto Val = LLVMGetEnumAttributeValue(SrcA);
-          auto DstA = LLVMCreateEnumAttribute(Ctx, k, Val);
-          LLVMAddAttributeAtIndex(F, i, DstA);
+      if (LLVMGetAttributeCountAtIndex(Cur, i) > 0) {
+        for (unsigned k = 0, e = LLVMGetLastEnumAttributeKind(); k < e; ++k) {
+          if (auto SrcA = LLVMGetEnumAttributeAtIndex(Cur, i, k)) {
+            auto Val = LLVMGetEnumAttributeValue(SrcA);
+            auto DstA = LLVMCreateEnumAttribute(Ctx, k, Val);
+            LLVMAddAttributeAtIndex(F, i, DstA);
+          }
         }
       }
     }