Index: llvm/include/llvm/Analysis/LoopInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/LoopInfoImpl.h
+++ llvm/include/llvm/Analysis/LoopInfoImpl.h
@@ -200,8 +200,6 @@
     }
   }
 
-  // Make sure there is only one exit out of the preheader.
-  assert(Out && "Header of loop has no predecessors from outside loop?");
   return Out;
 }
 
Index: llvm/test/CodeGen/AMDGPU/loop_header_nopred.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/loop_header_nopred.mir
@@ -0,0 +1,55 @@
+# RUN: llc -march=amdgcn -o - -run-pass=block-placement -mcpu=gfx1010 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefix=GCN %s
+
+# Used to fail with
+# Assertion `Out && "Header of loop has no predecessors from outside loop?"
+
+# GCN: name: loop_header_nopred
+# GCN: S_ENDPGM
+---
+name:            loop_header_nopred
+body:             |
+  bb.0:
+    successors: %bb.1(0x80000000)
+
+  bb.1:
+    successors: %bb.2(0x40000000), %bb.3(0x40000000)
+
+    S_CBRANCH_VCCZ %bb.3, implicit $vcc
+    S_BRANCH %bb.2
+
+  bb.2:
+    successors: %bb.3(0x80000000)
+
+  bb.3:
+    successors: %bb.4(0x40000000), %bb.6(0x40000000)
+
+    SI_MASK_BRANCH %bb.6, implicit $exec
+    S_BRANCH %bb.4
+
+  bb.4:
+    successors: %bb.5(0x04000000), %bb.4(0x7c000000)
+
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_NOP 0
+    S_CBRANCH_EXECZ %bb.4, implicit $exec
+
+  bb.5:
+    successors: %bb.6(0x80000000)
+
+  bb.6:
+    successors: %bb.7(0x04000000), %bb.1(0x7c000000)
+
+    S_CBRANCH_VCCZ %bb.1, implicit $vcc
+
+  bb.7:
+    S_ENDPGM 0
+...