Index: lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1837,6 +1837,11 @@
   StringRef FormatStr;
   if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
     return nullptr;
+  // The rest of the function assumes the return value is an integer type.
+  // If the sprintf function is static, an earlier optimization pass could
+  // remove the return value and make it void.
+  if (!isa<IntegerType>(CI->getType()))
+    return nullptr;
 
   // If we just have a format string (nothing else crazy) transform it.
   if (CI->getNumArgOperands() == 2) {
Index: test/Transforms/InstCombine/sprintf-void.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/sprintf-void.ll
@@ -0,0 +1,19 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+@hello_world = constant [13 x i8] c"hello world\0A\00"
+
+declare void @sprintf(i8*, i8*, ...)
+
+; Check that a sprintf call, that would otherwise be optimized, but with
+; optimized out return type, doesn't crash the optimizer.
+
+define void @test_simplify1(i8* %dst) {
+; CHECK-LABEL: @test_simplify1(
+  %fmt = getelementptr [13 x i8], [13 x i8]* @hello_world, i32 0, i32 0
+  call void (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt)
+; CHECK-NEXT: call void (i8*, i8*, ...) @sprintf(i8* %dst, i8* getelementptr inbounds ([13 x i8], [13 x i8]* @hello_world, i32 0, i32 0))
+  ret void
+; CHECK-NEXT: ret void
+}