Index: flang/docs/FortranLLVMTestSuite.md
===================================================================
--- flang/docs/FortranLLVMTestSuite.md
+++ flang/docs/FortranLLVMTestSuite.md
@@ -38,6 +38,13 @@
 environment variable to `1` in order to avoid test failures due to warnings
 about INEXACT signaling exceptions.
 
+Note that the reference outputs are by default matched exactly. If you see
+failures in FCVS when running the test-suite, you might want to try configuring
+it with `-DFCVS_ALLOW_FLEXIBLE_OUTPUT:BOOL=ON`. This will relax the checking for
+some of the tests which are known to be problematic (usually because they use
+Fortran features that are not very strictly specified in the standard, such as
+list-directed output).
+
 
 ## Running the SPEC CPU 2017