Index: llvm/include/llvm/IR/Attributes.h
===================================================================
--- llvm/include/llvm/IR/Attributes.h
+++ llvm/include/llvm/IR/Attributes.h
@@ -483,6 +483,9 @@
   LLVM_NODISCARD AttributeList addAttributesAtIndex(LLVMContext &C,
                                                     unsigned Index,
                                                     const AttrBuilder &B) const;
+  LLVM_NODISCARD AttributeList addAttributesAtIndex(LLVMContext &C,
+                                                    unsigned Index,
+                                                    AttributeSet AS) const;
 
   /// Add a function attribute to the list. Returns a new list because
   /// attribute lists are immutable.
@@ -512,6 +515,11 @@
     return addAttributesAtIndex(C, FunctionIndex, B);
   }
 
+  LLVM_NODISCARD AttributeList addFnAttributes(LLVMContext &C,
+                                               AttributeSet AS) const {
+    return addAttributesAtIndex(C, FunctionIndex, AS);
+  }
+
   /// Add a return value attribute to the list. Returns a new list because
   /// attribute lists are immutable.
   LLVM_NODISCARD AttributeList addRetAttribute(LLVMContext &C,
@@ -532,6 +540,10 @@
                                                 const AttrBuilder &B) const {
     return addAttributesAtIndex(C, ReturnIndex, B);
   }
+  LLVM_NODISCARD AttributeList addRetAttributes(LLVMContext &C,
+                                                AttributeSet AS) const {
+    return addAttributesAtIndex(C, ReturnIndex, AS);
+  }
 
   /// Add an argument attribute to the list. Returns a new list because
   /// attribute lists are immutable.
@@ -561,6 +573,11 @@
                                                   const AttrBuilder &B) const {
     return addAttributesAtIndex(C, ArgNo + FirstArgIndex, B);
   }
+  LLVM_NODISCARD AttributeList addParamAttributes(LLVMContext &C,
+                                                  unsigned ArgNo,
+                                                  AttributeSet AS) const {
+    return addAttributesAtIndex(C, ArgNo + FirstArgIndex, AS);
+  }
 
   /// Remove the specified attribute at the specified index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
@@ -947,12 +964,11 @@
   AttrBuilder(const AttrBuilder &) = delete;
   AttrBuilder(AttrBuilder &&) = default;
 
-  AttrBuilder(const Attribute &A) {
-    addAttribute(A);
-  }
+  explicit AttrBuilder(const Attribute &A) { addAttribute(A); }
+
+  explicit AttrBuilder(AttributeSet AS);
 
   AttrBuilder(AttributeList AS, unsigned Idx);
-  AttrBuilder(AttributeSet AS);
 
   void clear();
 
@@ -978,15 +994,24 @@
   /// Remove the attributes from the builder.
   AttrBuilder &removeAttributes(AttributeList A, uint64_t WithoutIndex);
 
+  /// Remove the attributes from the builder.
+  AttrBuilder &removeAttributes(AttributeSet AS);
+
   /// Remove the target-dependent attribute to the builder.
   AttrBuilder &removeAttribute(StringRef A);
 
   /// Add the attributes from the builder.
   AttrBuilder &merge(const AttrBuilder &B);
 
+  /// Add the attributes from the builder.
+  AttrBuilder &merge(AttributeSet AS);
+
   /// Remove the attributes from the builder.
   AttrBuilder &remove(const AttrBuilder &B);
 
+  /// Remove the attribute from the builder.
+  AttrBuilder &remove(Attribute A);
+
   /// Return true if the builder has any attribute that's in the
   /// specified builder.
   bool overlaps(const AttrBuilder &B) const;
Index: llvm/lib/IR/Attributes.cpp
===================================================================
--- llvm/lib/IR/Attributes.cpp
+++ llvm/lib/IR/Attributes.cpp
@@ -1264,6 +1264,29 @@
   return setAttributesAtIndex(C, Index, AttributeSet::get(C, Merged));
 }
 
+AttributeList AttributeList::addAttributesAtIndex(LLVMContext &C,
+                                                  unsigned Index,
+                                                  AttributeSet AS) const {
+  if (!AS.hasAttributes())
+    return *this;
+
+  if (!pImpl)
+    return AttributeList::get(C, {{Index, AS}});
+
+#ifndef NDEBUG
+  // FIXME it is not obvious how this should work for alignment. For now, say
+  // we can't change a known alignment.
+  const MaybeAlign OldAlign = getAttributes(Index).getAlignment();
+  const MaybeAlign NewAlign = AS.getAlignment();
+  assert((!OldAlign || !NewAlign || OldAlign == NewAlign) &&
+         "Attempt to change alignment!");
+#endif
+
+  AttrBuilder Merged(getAttributes(Index));
+  Merged.merge(AS);
+  return setAttributesAtIndex(C, Index, AttributeSet::get(C, Merged));
+}
+
 AttributeList AttributeList::addParamAttribute(LLVMContext &C,
                                                ArrayRef<unsigned> ArgNos,
                                                Attribute A) const {
@@ -1617,7 +1640,13 @@
 }
 
 AttrBuilder &AttrBuilder::removeAttributes(AttributeList A, uint64_t Index) {
-  remove(A.getAttributes(Index));
+  removeAttributes(A.getAttributes(Index));
+  return *this;
+}
+
+AttrBuilder &AttrBuilder::removeAttributes(AttributeSet AS) {
+  for (Attribute A : AS)
+    remove(A);
   return *this;
 }
 
@@ -1760,6 +1789,12 @@
   return *this;
 }
 
+AttrBuilder &AttrBuilder::merge(AttributeSet AS) {
+  for(Attribute A : AS)
+    addAttribute(A);
+  return *this;
+}
+
 AttrBuilder &AttrBuilder::remove(const AttrBuilder &B) {
   // FIXME: What if both have an int/type attribute, but they don't match?!
   for (unsigned Index = 0; Index < Attribute::NumIntAttrKinds; ++Index)
@@ -1778,6 +1813,13 @@
   return *this;
 }
 
+AttrBuilder &AttrBuilder::remove(Attribute A) {
+  if (A.isStringAttribute())
+    return removeAttribute(A.getKindAsString());
+  else
+    return removeAttribute(A.getKindAsEnum());
+}
+
 bool AttrBuilder::overlaps(const AttrBuilder &B) const {
   // First check if any of the target independent attributes overlap.
   if ((Attrs & B.Attrs).any())
Index: llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1377,7 +1377,7 @@
     return AL;
 
   // Remove the readonly, readnone, and statepoint function attributes.
-  AttrBuilder FnAttrs = AL.getFnAttrs();
+  AttrBuilder FnAttrs(AL.getFnAttrs());
   for (auto Attr : FnAttrsToStrip)
     FnAttrs.removeAttribute(Attr);
 
@@ -1387,8 +1387,7 @@
   }
 
   // Just skip parameter and return attributes for now
-  return AttributeList::get(Ctx, AttributeList::FunctionIndex,
-                            AttributeSet::get(Ctx, FnAttrs));
+  return AttributeList::get(Ctx, AttributeList::FunctionIndex, FnAttrs);
 }
 
 /// Helper function to place all gc relocates necessary for the given
Index: llvm/unittests/IR/AttributesTest.cpp
===================================================================
--- llvm/unittests/IR/AttributesTest.cpp
+++ llvm/unittests/IR/AttributesTest.cpp
@@ -55,7 +55,7 @@
 
   AttributeList SetA = AttributeList::get(C, ASs);
   AttributeList SetB =
-      SetA.removeParamAttributes(C, 0, ASs[1].getParamAttrs(0));
+      SetA.removeParamAttributes(C, 0, AttrBuilder(ASs[1].getParamAttrs(0)));
   EXPECT_NE(SetA, SetB);
 }