diff --git a/src/plugins/clangcodemodel/clangutils.cpp b/src/plugins/clangcodemodel/clangutils.cpp
index 573d1be1fd1..1d704c8a88b 100644
--- a/src/plugins/clangcodemodel/clangutils.cpp
+++ b/src/plugins/clangcodemodel/clangutils.cpp
@@ -96,6 +96,7 @@ public:
         optionsBuilder.enableExceptions();
 
         optionsBuilder.addDefineToAvoidIncludingGccOrMinGwIntrinsics();
+        optionsBuilder.addDefineFloat128ForMingw();
         optionsBuilder.addToolchainAndProjectDefines();
         optionsBuilder.undefineCppLanguageFeatureMacrosForMsvc2015();
 
diff --git a/src/plugins/clangrefactoring/refactoringcompileroptionsbuilder.cpp b/src/plugins/clangrefactoring/refactoringcompileroptionsbuilder.cpp
index ca79ca5e4ab..5fa28940f5a 100644
--- a/src/plugins/clangrefactoring/refactoringcompileroptionsbuilder.cpp
+++ b/src/plugins/clangrefactoring/refactoringcompileroptionsbuilder.cpp
@@ -130,6 +130,7 @@ Utils::SmallStringVector RefactoringCompilerOptionsBuilder::build(CppTools::Proj
     optionsBuilder.addOptionsForLanguage(/*checkForBorlandExtensions*/ true);
     optionsBuilder.enableExceptions();
 
+    optionsBuilder.addDefineFloat128ForMingw();
     optionsBuilder.addDefineToAvoidIncludingGccOrMinGwIntrinsics();
     optionsBuilder.addToolchainAndProjectDefines();
     optionsBuilder.undefineCppLanguageFeatureMacrosForMsvc2015();
diff --git a/src/plugins/clangstaticanalyzer/clangstaticanalyzerruncontrol.cpp b/src/plugins/clangstaticanalyzer/clangstaticanalyzerruncontrol.cpp
index 4185b6bfaa0..10cb6115ba5 100644
--- a/src/plugins/clangstaticanalyzer/clangstaticanalyzerruncontrol.cpp
+++ b/src/plugins/clangstaticanalyzer/clangstaticanalyzerruncontrol.cpp
@@ -175,6 +175,7 @@ public:
         optionsBuilder.addOptionsForLanguage(false);
         optionsBuilder.enableExceptions();
 
+        optionsBuilder.addDefineFloat128ForMingw();
         optionsBuilder.addDefineToAvoidIncludingGccOrMinGwIntrinsics();
         const Core::Id type = projectPart.toolchainType;
         if (type != ProjectExplorer::Constants::MSVC_TOOLCHAIN_TYPEID)
diff --git a/src/plugins/cpptools/compileroptionsbuilder.cpp b/src/plugins/cpptools/compileroptionsbuilder.cpp
index c62feb94cd2..a2b2ed3ba68 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.cpp
+++ b/src/plugins/cpptools/compileroptionsbuilder.cpp
@@ -368,6 +368,14 @@ void CompilerOptionsBuilder::undefineCppLanguageFeatureMacrosForMsvc2015()
     }
 }
 
+void CompilerOptionsBuilder::addDefineFloat128ForMingw()
+{
+    // TODO: Remove once this is fixed in clang >= 3.9.
+    // https://llvm.org/bugs/show_bug.cgi?id=30685
+    if (m_projectPart.toolchainType == ProjectExplorer::Constants::MINGW_TOOLCHAIN_TYPEID)
+        addDefine("#define __float128 void");
+}
+
 QString CompilerOptionsBuilder::includeOption() const
 {
     return QLatin1String("-I");
diff --git a/src/plugins/cpptools/compileroptionsbuilder.h b/src/plugins/cpptools/compileroptionsbuilder.h
index 4cae4bb353d..ced3c0af1ba 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.h
+++ b/src/plugins/cpptools/compileroptionsbuilder.h
@@ -58,6 +58,8 @@ public:
     void addMsvcCompatibilityVersion();
     void undefineCppLanguageFeatureMacrosForMsvc2015();
 
+    void addDefineFloat128ForMingw();
+
 protected:
     virtual bool excludeDefineDirective(const QByteArray &defineDirective) const;
     virtual bool excludeHeaderPath(const QString &headerPath) const;