[REG 5.14.0-5.14.1] Unable to compile with gcc-4.9

I installed Qt 5.14.1 on Centos-7 a few days ago, but the problem I'm facing is nothing will build. Not even the included examples. They all fail with the following warning:

#error “Qt requires C++11 support”

I have tried the obvious fixes that came up when googling, but they have no effect:

CONFIG = c+11

QMAKE_CXXFLAGS = -std=c+11

Other versions of Qt (5.12.4, 5.12.6) work just fine, but unfortunately I need a bug fix in 5.14.1.

Here is some relevant information to my system:

cat /etc/os-release

NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
uname -r
3.10.0-693.21.1.el7.x86_64

gcc --version
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

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