Index: llvm/lib/CodeGen/IfConversion.cpp
===================================================================
--- llvm/lib/CodeGen/IfConversion.cpp
+++ llvm/lib/CodeGen/IfConversion.cpp
@@ -1584,8 +1584,11 @@
     MergeBlocks(BBI, *CvtBBI, false);
   }
 
-  // Keep the CFG updated.
-  BBI.BB->removeSuccessor(&CvtMBB, true);
+  // Keep the CFG updated. If CvtMBB and NextMBB happen to be the same we skip
+  // removing CvtMBB as successor since that would also remove NextMBB (which we
+  // want to keep).
+  if (&CvtMBB != &NextMBB)
+    BBI.BB->removeSuccessor(&CvtMBB, true);
 
   // If 'true' block has a 'false' successor, add an exit branch to it.
   if (HasEarlyExit) {
Index: llvm/test/CodeGen/ARM/ifcvt_triangleSameCvtNext.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/ARM/ifcvt_triangleSameCvtNext.mir
@@ -0,0 +1,30 @@
+# RUN: llc -mtriple=arm-apple-ios -run-pass=if-converter -verify-machineinstrs %s -o - | FileCheck %s
+...
+---
+name:            foo
+body:             |
+  bb.0:
+    Bcc %bb.2, 1, $cpsr
+
+  bb.1:
+    $sp = tADDspi $sp, 2, 14, _
+    B %bb.1
+
+  bb.2:
+    Bcc %bb.3, 0, $cpsr
+    B %bb.2
+
+  bb.3:
+    Bcc %bb.1, 1, $cpsr
+    B %bb.1
+...
+
+# Both branches in bb.3 jump to bb.1. IfConversion treats it as a triangle with
+# CvtBB and NextBB both being bb.1. We must make sure that bb.3 at the end still
+# has bb.1 as a successor or the CFG will be broken and verifiers will complain
+# that the block ends with a branch but the successor list is empty.
+
+# CHECK:     bb.3:
+# CHECK:       successors: %bb.1
+# CHECK:       $sp = tADDspi $sp, 2, 1, $cpsr
+# CHECK:       B %bb.1