diff --git a/lib/Format/BreakableToken.cpp b/lib/Format/BreakableToken.cpp
index 20e3e5b1dfd665abb79af9e7ba3276ec0f1b971d..b9e48e63019c1e42e1240394623f62fe41e67f23 100644
--- a/lib/Format/BreakableToken.cpp
+++ b/lib/Format/BreakableToken.cpp
@@ -545,15 +545,18 @@ void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
 }
 
 BreakableToken::Split BreakableBlockComment::getSplitBefore(
-    unsigned LineIndex,
-    unsigned PreviousEndColumn,
-    unsigned ColumnLimit,
+    unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
     llvm::Regex &CommentPragmasRegex) const {
   if (!mayReflow(LineIndex, CommentPragmasRegex))
     return Split(StringRef::npos, 0);
   StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
-  return getReflowSplit(TrimmedContent, ReflowPrefix, PreviousEndColumn,
-                        ColumnLimit);
+  Split Result = getReflowSplit(TrimmedContent, ReflowPrefix, PreviousEndColumn,
+                                ColumnLimit);
+  // Result is relative to TrimmedContent. Adapt it relative to
+  // Content[LineIndex].
+  if (Result.first != StringRef::npos)
+    Result.first += Content[LineIndex].size() - TrimmedContent.size();
+  return Result;
 }
 
 unsigned BreakableBlockComment::getReflownColumn(
@@ -633,17 +636,12 @@ void BreakableBlockComment::replaceWhitespaceBefore(
         /*CurrentPrefix=*/ReflowPrefix, InPPDirective, /*Newlines=*/0,
         /*Spaces=*/0);
     // Check if we need to also insert a break at the whitespace range.
-    // For this we first adapt the reflow split relative to the beginning of the
-    // content.
     // Note that we don't need a penalty for this break, since it doesn't change
     // the total number of lines.
-    Split BreakSplit = SplitBefore;
-    BreakSplit.first += TrimmedContent.data() - Content[LineIndex].data();
     unsigned ReflownColumn =
         getReflownColumn(TrimmedContent, LineIndex, PreviousEndColumn);
-    if (ReflownColumn > ColumnLimit) {
-      insertBreak(LineIndex, 0, BreakSplit, Whitespaces);
-    }
+    if (ReflownColumn > ColumnLimit)
+      insertBreak(LineIndex, 0, SplitBefore, Whitespaces);
     return;
   }
 
diff --git a/unittests/Format/FormatTestComments.cpp b/unittests/Format/FormatTestComments.cpp
index 600132ec4b86c0b10d86e7ad7d0910a5763fe55d..c8ebebc58ad491ef2686a84e39d4d23e941d071d 100644
--- a/unittests/Format/FormatTestComments.cpp
+++ b/unittests/Format/FormatTestComments.cpp
@@ -2787,6 +2787,24 @@ TEST_F(FormatTestComments, AlignsBlockCommentDecorations) {
                    "* long */",
                    getLLVMStyleWithColumns(20)));
 }
+
+TEST_F(FormatTestComments, NoCrush_Bug34236) {
+  // This is a test case from a crasher reported in:
+  // https://bugs.llvm.org/show_bug.cgi?id=34236
+  // Temporarily disable formatting for readability.
+  // clang-format off
+  EXPECT_EQ(
+"/*                                                                */ /*\n"
+"                                                                      *       a\n"
+"                                                                      * b c\n"
+"                                                                      * d*/",
+      format(
+"/*                                                                */ /*\n"
+" *       a b\n"
+" *       c     d*/",
+          getLLVMStyleWithColumns(80)));
+  // clang-format on
+}
 } // end namespace
 } // end namespace format
 } // end namespace clang