diff --git a/src/llvm/builder.cr b/src/llvm/builder.cr
index 741f9ee8eb5c..3f2060b32084 100644
--- a/src/llvm/builder.cr
+++ b/src/llvm/builder.cr
@@ -239,11 +239,13 @@ class LLVM::Builder
     end
   {% end %}
 
-  def not(value, name = "")
-    # check_value(value)
+  {% for name in %w(not neg fneg) %}
+    def {{name.id}}(value, name = "")
+      # check_value(value)
 
-    Value.new LibLLVM.build_not(self, value, name)
-  end
+      Value.new LibLLVM.build_{{name.id}}(self, value, name)
+    end
+  {% end %}
 
   def unreachable
     Value.new LibLLVM.build_unreachable(self)
diff --git a/src/llvm/lib_llvm/core.cr b/src/llvm/lib_llvm/core.cr
index de6f04010cfa..ff3327a3f78d 100644
--- a/src/llvm/lib_llvm/core.cr
+++ b/src/llvm/lib_llvm/core.cr
@@ -239,6 +239,8 @@ lib LibLLVM
   fun build_or = LLVMBuildOr(BuilderRef, lhs : ValueRef, rhs : ValueRef, name : Char*) : ValueRef
   fun build_xor = LLVMBuildXor(BuilderRef, lhs : ValueRef, rhs : ValueRef, name : Char*) : ValueRef
   fun build_not = LLVMBuildNot(BuilderRef, value : ValueRef, name : Char*) : ValueRef
+  fun build_neg = LLVMBuildNeg(BuilderRef, value : ValueRef, name : Char*) : ValueRef
+  fun build_fneg = LLVMBuildFNeg(BuilderRef, value : ValueRef, name : Char*) : ValueRef
 
   fun build_malloc = LLVMBuildMalloc(BuilderRef, ty : TypeRef, name : Char*) : ValueRef
   fun build_array_malloc = LLVMBuildArrayMalloc(BuilderRef, ty : TypeRef, val : ValueRef, name : Char*) : ValueRef